diff --git a/Documentation/config-project-config.txt b/Documentation/config-project-config.txt
index dfc38c3..7a0e305 100644
--- a/Documentation/config-project-config.txt
+++ b/Documentation/config-project-config.txt
@@ -319,11 +319,64 @@
 
 [[content_merge]]submit.mergeContent::
 +
-Defines whether Gerrit will try to
-do a content merge when a path conflict occurs. Valid values are
-'true', 'false', or 'INHERIT'.  Default is 'INHERIT'. This option can
-be modified by any project owner through the project console, `Browse`
-> `Repositories` > my/project > `Allow content merges`.
+Defines whether Gerrit will try to do a content merge when a path conflict
+occurs while submitting a change.
++
+A path conflict occurs when the same file has been changed on both sides of a
+merge, e.g. when the same file has been touched in a change and concurrently in
+the target branch.
++
+Doing a content merge means that Gerrit attempts to merge the conflicting file
+contents from both sides of the merge. This is successful if the touched lines
+(plus some surrounding context lines) do not overlap (i.e. both sides touch
+distinct lines).
++
+NOTE: The content merge setting is not relevant when
+link:#fast_forward_only[fast forward only] is configured as the
+link:#submit.action[submit action] because in this case Gerrit will never
+perform a merge, rebase or cherry-pick on submit.
++
+If content merges are disabled, the submit button in the Gerrit web UI is
+disabled, if any path conflict would occur on submitting the change. Users then
+need to rebase the change manually to resolve the path conflict and then get
+the change re-approved so that they can submit it.
++
+NOTE: If only distinct lines have been touched on both sides, rebasing the
+change from the Gerrit UI is sufficient to resolve the path conflict, since the
+rebase action always does the rebase with content merge enabled.
++
+The advantage of enabling content merges on submit is that it makes it less
+likely that change submissions are rejected due to conflicts. Each change
+submission that goes through with content merge, but would be rejected
+otherwise, saves the user from needing to do extra work to get the change
+submitted (rebase the change, get it re-approved and then submit it again).
++
+On the other hand, disabling content merges decreases the chance of breaking
+branches by submitting content merges of incompatible modifications in the same
+file, e.g. a function is removed on one side and a new usage of that function
+is added on the other side. Note, that the chance of breaking a branch by
+incompatible modifications is only reduced, but not eliminated, e.g. even with
+content merges disabled it's possible that a function is removed in one file
+and a new usage of that function is added in another file.
++
+The huge drawback of disabling content merge is that users need to do extra
+work when a change isn't submittable due to a path conflict which could be
+avoided if content merge was enabled (see above). In addition to this, it also
+confuses and frustrates users if a change submission is rejected by Gerrit due
+to a path conflict, but then when they rebase the change manually they do not
+see any conflict (because manual rebases are always done with content merge
+enabled).
++
+In general, the stability gain of disabling content merges is not worth the
+overhead and confusion that this adds for users, which is why disabling content
+merges is highly discouraged.
++
+Valid values are `true`, `false`, or `INHERIT`.
++
+The default is `INHERIT`.
++
+NOTE: Project owners can also set this option in the Gerrit UI:
+`Browse` > `Repositories` > my/repository > `Allow content merges`.
 
 [[submit.action]]submit.action::
 +
@@ -342,55 +395,136 @@
 [[merge_if_necessary]]
 * 'merge if necessary':
 +
-If the change being submitted is a strict superset of the destination branch,
-then the branch is fast-forwarded to the change. If not, then a merge commit is
-automatically created. This is identical to the classical `git merge` behavior,
- or `git merge --ff`.
+With this action, when a change is being submitted, Gerrit fast-forwards the
+target branch if possible, and otherwise creates a merge commit automatically.
++
+A fast-forward is possible if the commit that represents the current patch set
+of the change has the current head of the target branch in its parent lineage.
++
+If a fast-forward is not possible, Gerrit automatically creates a merge commit
+that merges the current patch set of the change into the target branch and then
+the target branch is fast-forwarded to the merge commit.
++
+The behavior of this submit action is identical with the classical `git merge`
+behavior, or
+link:https://git-scm.com/docs/git-merge#Documentation/git-merge.txt---ff[git
+merge --ff].
++
+With this submit action the commits that have been reviewed and approved are
+retained in the git history of the target branch. This means, by looking at the
+history of the target branch, you can see for all commits when they were
+originally committed and on which parent commit they were originally based.
 
 [[always_merge]]
 [[merge_always]]
 * 'merge always':
 +
-Always produce a merge commit, even if the change is a strict superset of the
-destination branch. This is identical to the behavior of `git merge --no-ff`,
-and may be useful if the project needs to follow submits with
-`git log --first-parent`.
+With this action, when a change is being submitted, Gerrit always creates a
+merge commit, even if a fast-forward is possible.
++
+This is identical to the behavior of
+link:https://git-scm.com/docs/git-merge#Documentation/git-merge.txt---no-ff[git merge --no-ff].
++
+With this submit action the commits that have been reviewed and approved are
+retained in the git history of the target branch. This means, by looking at the
+history of the target branch, you can see for all commits when they were
+originally committed and on which parent commit they were originally based. In
+addition, from the merge commits you can see when the changes were submitted
+and it's possible to follow submissions with `git log --first-parent`.
 
 [[rebase_if_necessary]]
 * 'rebase if necessary':
 +
-If the change being submitted is a strict superset of the destination branch,
-then the branch is fast-forwarded to the change. If not, then the change is
-automatically rebased and then the branch is fast-forwarded to the change.
+With this action, when a change is being submitted, Gerrit fast-forwards the
+target branch if possible, and otherwise does a rebase automatically.
 +
-When Gerrit tries to do a merge, by default the merge will only succeed if
-there is no path conflict. A path conflict occurs when the same file has also
-been changed on the other side of the merge.
+A fast-forward is possible if the commit that represents the current patch set
+of the change has the current head of the target branch in its parent lineage.
++
+If a fast-forward is not possible, Gerrit automatically rebases the current
+patch set of the change on top of the current head of the target branch and
+then the target branch is fast-forwarded to the rebased commit.
++
+With this submit action, when a rebase is performed, the original commits that
+have been reviewed and approved do not become part of the target branch's
+history. This means the information on when the original commits were committed
+and on which parent they were based is not retained in the branch history.
++
+Using this submit action results in a linear history of the target branch,
+unless merge commits are being submitted. For some people this is an advantage
+since they find the linear history easier to read.
++
+NOTE: Rebasing merge commits is not supported. If a change with a merge commit
+is submitted the link:#merge_if_necessary[merge if necessary] submit action is
+applied.
++
+When rebasing the patchset, Gerrit automatically appends onto the end of the
+commit message a short summary of the change's approvals, and a URL link back
+to the change in the web UI (see link:#submit-footers[below]). If a fast-forward
+is done no footers are added.
 
 [[rebase_always]]
 * 'rebase always':
 +
-Basically, the same as `rebase if necessary`, but it creates a new patchset
-even if fast forward is possible and like `cherry pick` it ensures footers such
-as `Change-Id`, `Reviewed-On`, and others are present in resulting commit that
-is merged.
+With this action, when a change is being submitted, Gerrit always does a
+rebase, even if a fast-forward is possible.
 +
-Thus, `rebase always` can be considered similar to `cherry pick`, but with the
-important distinction that `rebase always` does not ignore dependencies.
+With this submit action, the original commits that have been reviewed and
+approved do not become part of the target branch's history. This means the
+information on when the original commits were committed and on which parent
+they were based is not retained in the branch history.
++
+Using this submit action results in a linear history of the target branch,
+unless merge commits are being submitted. For some people this is an advantage
+since they find the linear history easier to read.
++
+NOTE: Rebasing merge commits is not supported. If a change with a merge commit
+is submitted the link:#merge_if_necessary[merge if necessary] submit action is
+applied.
++
+When rebasing the patchset, Gerrit automatically appends onto the end of the
+commit message a short summary of the change's approvals, and a URL link back
+to the change in the web UI (see link:#submit-footers[below]).
++
+The footers that are added are exactly the same footers that are also added by
+the link:cherry_pick[cherry pick] action. Thus, the `rebase always` action can
+be considered similar to the `cherry pick` action, but with the important
+distinction that `rebase always` does not ignore dependencies, which is why
+using the `rebase always` action should be preferred over the `cherry pick`
+submit action.
 
 [[fast_forward_only]]
-* 'fast forward only':
+* 'fast forward only' (usage generally not recommended):
 +
-With this action Gerrit does not create merge commits on submitting a change.
-Merge commits may still be submitted, but they must be created on the client
-prior to uploading to Gerrit for review.
+With this action a change can only be submitted if at submit time the target
+branch can be fast-forwarded to the commit that represents the current patch
+set of the change. This means in order for a change to be submittable its
+current patch set must have the current head of the target branch in its parent
+lineage.
 +
-To submit a change, the change must be a strict superset of the destination
-branch. That is, the change must already contain the tip of the destination
-branch at submit time.
+The advantage of using this action is that the target branch is always updated
+to the exact commit that has been reviewed and approved. In particular, if CI
+verification is configured, this means that the CI verified the exact commit to
+which the target branch is being fast-forwarded on submit (assuming no approval
+copying is configured for CI votes).
++
+The huge drawback of using this action is that whenever one change is submitted
+all other open changes for the same branch, that are not successors of the
+submitted change, become non-submittable, since the target branch can no longer
+be fast-forwarded to their current patch sets. Making these changes submittable
+again requires rebasing and re-approving/re-verifying them. For most projects
+this causes an unreasonable amount of overhead that doesn't justify the
+stability gain by verifying exact commits so that using this submit action is
+generally discouraged. Using this action should only be considered for projects
+that have a low frequency of changes and that have special requirements to
+never break any target branch.
++
+NOTE: With this submit action Gerrit does not create merge commits on
+submitting a change, but merge commits that are created on the client, prior to
+uploading to Gerrit for review, may still be submitted.
 
 [[cherry_pick]]
-* 'cherry pick' (usage not recommended, user link:#rebase_always[rebase always]
+* 'cherry pick' (usage not recommended, use link:#rebase_always[rebase always]
 instead):
 +
 With this submit action Gerrit always performs a cherry pick of the current
@@ -416,7 +550,7 @@
 +
 When cherry picking the patchset, Gerrit automatically appends onto the end of
 the commit message a short summary of the change's approvals, and a URL link
-back to the change on the web.
+back to the change in the web UI (see link:#submit-footers[below]).
 +
 Using this submit action is not recommended because it ignores change
 dependencies, instead link:#rebase_always[rebase always] should be used which
@@ -436,6 +570,49 @@
 +
 If `submit.action` is not set, the default is 'merge if necessary'.
 +
+NOTE: The different submit actions are also described in the
+link:https://docs.google.com/presentation/d/1C73UgQdzZDw0gzpaEqIC6SPujZJhqamyqO1XOHjH-uk/edit#slide=id.g4d6c16487b_1_800[Gerrit - Concepts and Workflows]
+presentation, where their behavior is visualized by git commit graphs.
++
+NOTE: If Gerrit performs a merge, rebase or cherry-pick as part of the
+change submission (true for all submit actions, except for
+link:#fast_forward_only[fast forward only]), it is controlled by the
+link:#submit.mergeContent[mergeContent] setting whether a content merge is
+performed when there is a path conflict.
++
+NOTE: If Gerrit performs a merge, rebase or cherry-pick as part of the
+change submission (true for all submit actions, except for
+link:#fast_forward_only[fast forward only]), it can be that trying to submit
+a change would fail due to Git conflicts (if the same lines were modified
+concurrently, or if link:#submit.mergeContent[mergeContent] is disabled also if
+the same files were modified concurrently). In this case the submit button in
+the Gerrit web UI is disabled and a tooltip on the disabled submit button
+informs about the change being non-mergeable.
++
+[[submit-footers]]
+--
+NOTE: If Gerrit performs a rebase or cherry-pick as part of the change
+submission (true for link:#rebase_if_necessary[rebase if necessary],
+link:#rebase_always[rebase always] and link:#cherry_pick[cherry pick]) Gerrit
+inserts additional footers into the commit message of the newly created
+commit: +
+ +
+* `Change-Id: <change-id>` (only if this footer is not already present, see
+  link:user-changeid.html[Change-Id]) +
+* `Reviewed-on: <change-url>` (links to the change in Gerrit where this commit
+  was reviewed) +
+* `Reviewed-by: <reviewer>` (once for every reviewer with a positive
+  `Code-Review` vote) +
+* `Tested-by: <reviewer>` (once for every reviewer with a positive `Verified`
+  vote) +
+* `<label-name>: <reviewer>` (once for every reviewer with a positive vote on
+  any other label) +
+ +
+In addition, plugins that implement a
+link:dev-plugins.html#change-message-modifier[Change Message Modifier] may add
+additional custom footers.
+--
++
 NOTE: For the value of `submit.action` in `project.config` use the exact
 spelling as given above, e.g. 'merge if necessary' (without the single quotes,
 but with the spaces).
diff --git a/Documentation/dev-roles.txt b/Documentation/dev-roles.txt
index cecaedc..d8f7e11 100644
--- a/Documentation/dev-roles.txt
+++ b/Documentation/dev-roles.txt
@@ -66,11 +66,12 @@
 link:https://groups.google.com/d/forum/repo-discuss[repo-discuss,role=external,window=_blank]
 mailing list):
 
-* become member of the `gerrit-verifiers` group, which allows to:
+* become member of the `gerrit-trusted-contributors` group, which allows to:
 ** vote on the `Verified` and `Code-Style` labels
 ** edit hashtags on all changes
 ** edit topics on all open changes
 ** abandon changes
+** revert changes
 * approve posts to the
   link:https://groups.google.com/d/forum/repo-discuss[repo-discuss,role=external,window=_blank]
   mailing list
@@ -106,14 +107,14 @@
 have. In addition they have signed a link:dev-cla.html[contributor
 license agreement] which enables them to push changes.
 
-Regular contributors can ask to be added to the `gerrit-verifiers`
+Regular contributors can ask to be added to the `gerrit-trusted-contributors`
 group, which allows to:
 
 * add patch sets to changes of other users
 * propose project config changes (push changes for the
   `refs/meta/config` branch
 
-Being member of the `gerrit-verifiers` group includes further
+Being member of the `gerrit-trusted-contributors` group includes further
 permissions (see link:#supporter[supporter] section above).
 
 It's highly appreciated if contributors engage in code reviews,
diff --git a/Documentation/pg-plugin-endpoints.txt b/Documentation/pg-plugin-endpoints.txt
index f2a72f1..41f544d 100644
--- a/Documentation/pg-plugin-endpoints.txt
+++ b/Documentation/pg-plugin-endpoints.txt
@@ -141,6 +141,11 @@
 === header-title
 This endpoint wraps the title-text in the application header.
 
+=== cherrypick-main
+This endpoint is located in the cherrypick dialog. It has two slots `top`
+and `bottom` and `changes` as a parameter with the list of changes (or
+just the one change) to be cherrypicked.
+
 === confirm-revert-change
 This endpoint is inside the confirm revert dialog. By default it displays a
 generic confirmation message regarding reverting the change. Plugins may add
diff --git a/Documentation/user-notify.txt b/Documentation/user-notify.txt
index 20ad07c..24c35f0 100644
--- a/Documentation/user-notify.txt
+++ b/Documentation/user-notify.txt
@@ -18,8 +18,8 @@
 [[user]]
 == User Level Settings
 
-Individual users can configure email subscriptions by editing
-watched projects through Settings > Watched Projects with the web UI.
+Individual users can configure email subscriptions by editing their
+notifications in the Web UI under `Settings` > `Notifications`.
 
 Specific projects may be watched, or the special project
 `All-Projects` can be watched to watch all projects that
diff --git a/java/com/google/gerrit/server/index/group/GroupField.java b/java/com/google/gerrit/server/index/group/GroupField.java
index 775bd5e..dd6aa3b 100644
--- a/java/com/google/gerrit/server/index/group/GroupField.java
+++ b/java/com/google/gerrit/server/index/group/GroupField.java
@@ -16,11 +16,7 @@
 
 import static com.google.common.collect.ImmutableList.toImmutableList;
 import static com.google.gerrit.index.FieldDef.exact;
-import static com.google.gerrit.index.FieldDef.fullText;
-import static com.google.gerrit.index.FieldDef.integer;
-import static com.google.gerrit.index.FieldDef.prefix;
 import static com.google.gerrit.index.FieldDef.storedOnly;
-import static com.google.gerrit.index.FieldDef.timestamp;
 
 import com.google.common.base.MoreObjects;
 import com.google.gerrit.entities.Account;
@@ -28,6 +24,7 @@
 import com.google.gerrit.entities.InternalGroup;
 import com.google.gerrit.git.ObjectIds;
 import com.google.gerrit.index.FieldDef;
+import com.google.gerrit.index.IndexedField;
 import com.google.gerrit.index.SchemaUtil;
 import java.sql.Timestamp;
 import org.eclipse.jgit.lib.ObjectId;
@@ -40,49 +37,88 @@
  */
 public class GroupField {
   /** Legacy group ID. */
-  public static final FieldDef<InternalGroup, Integer> ID =
-      integer("id").build(g -> g.getId().get());
+  public static final IndexedField<InternalGroup, Integer> ID_FIELD =
+      IndexedField.<InternalGroup>integerBuilder("Id").required().build(g -> g.getId().get());
+
+  public static final IndexedField<InternalGroup, Integer>.SearchSpec ID_FIELD_SPEC =
+      ID_FIELD.integer("id");
 
   /** Group UUID. */
   public static final FieldDef<InternalGroup, String> UUID =
       exact("uuid").stored().build(g -> g.getGroupUUID().get());
 
   /** Group owner UUID. */
-  public static final FieldDef<InternalGroup, String> OWNER_UUID =
-      exact("owner_uuid").build(g -> g.getOwnerGroupUUID().get());
+  public static final IndexedField<InternalGroup, String> OWNER_UUID_FIELD =
+      IndexedField.<InternalGroup>stringBuilder("OwnerUUID")
+          .required()
+          .build(g -> g.getOwnerGroupUUID().get());
+
+  public static final IndexedField<InternalGroup, String>.SearchSpec OWNER_UUID_SPEC =
+      OWNER_UUID_FIELD.exact("owner_uuid");
 
   /** Timestamp indicating when this group was created. */
   // TODO(issue-15518): Migrate type for timestamp index fields from Timestamp to Instant
-  public static final FieldDef<InternalGroup, Timestamp> CREATED_ON =
-      timestamp("created_on").build(internalGroup -> Timestamp.from(internalGroup.getCreatedOn()));
+  public static final IndexedField<InternalGroup, Timestamp> CREATED_ON_FIELD =
+      IndexedField.<InternalGroup>timestampBuilder("CreatedOn")
+          .required()
+          .build(internalGroup -> Timestamp.from(internalGroup.getCreatedOn()));
+
+  public static final IndexedField<InternalGroup, Timestamp>.SearchSpec CREATED_ON_SPEC =
+      CREATED_ON_FIELD.timestamp("created_on");
 
   /** Group name. */
-  public static final FieldDef<InternalGroup, String> NAME =
-      exact("name").build(InternalGroup::getName);
+  public static final IndexedField<InternalGroup, String> NAME_FIELD =
+      IndexedField.<InternalGroup>stringBuilder("Name")
+          .required()
+          .size(200)
+          .build(InternalGroup::getName);
+
+  public static final IndexedField<InternalGroup, String>.SearchSpec NAME_SPEC =
+      NAME_FIELD.exact("name");
 
   /** Prefix match on group name parts. */
-  public static final FieldDef<InternalGroup, Iterable<String>> NAME_PART =
-      prefix("name_part").buildRepeatable(g -> SchemaUtil.getNameParts(g.getName()));
+  public static final IndexedField<InternalGroup, Iterable<String>> NAME_PART_FIELD =
+      IndexedField.<InternalGroup>iterableStringBuilder("NamePart")
+          .required()
+          .size(200)
+          .build(g -> SchemaUtil.getNameParts(g.getName()));
+
+  public static final IndexedField<InternalGroup, Iterable<String>>.SearchSpec NAME_PART_SPEC =
+      NAME_PART_FIELD.prefix("name_part");
 
   /** Group description. */
-  public static final FieldDef<InternalGroup, String> DESCRIPTION =
-      fullText("description").build(InternalGroup::getDescription);
+  public static final IndexedField<InternalGroup, String> DESCRIPTION_FIELD =
+      IndexedField.<InternalGroup>stringBuilder("Description").build(InternalGroup::getDescription);
+
+  public static final IndexedField<InternalGroup, String>.SearchSpec DESCRIPTION_SPEC =
+      DESCRIPTION_FIELD.fullText("description");
 
   /** Whether the group is visible to all users. */
-  public static final FieldDef<InternalGroup, String> IS_VISIBLE_TO_ALL =
-      exact("is_visible_to_all").build(g -> g.isVisibleToAll() ? "1" : "0");
+  public static final IndexedField<InternalGroup, String> IS_VISIBLE_TO_ALL_FIELD =
+      IndexedField.<InternalGroup>stringBuilder("IsVisibleToAll")
+          .required()
+          .size(1)
+          .build(g -> g.isVisibleToAll() ? "1" : "0");
 
-  public static final FieldDef<InternalGroup, Iterable<Integer>> MEMBER =
-      integer("member")
-          .buildRepeatable(
-              g -> g.getMembers().stream().map(Account.Id::get).collect(toImmutableList()));
+  public static final IndexedField<InternalGroup, String>.SearchSpec IS_VISIBLE_TO_ALL_SPEC =
+      IS_VISIBLE_TO_ALL_FIELD.exact("is_visible_to_all");
 
-  public static final FieldDef<InternalGroup, Iterable<String>> SUBGROUP =
-      exact("subgroup")
-          .buildRepeatable(
+  public static final IndexedField<InternalGroup, Iterable<Integer>> MEMBER_FIELD =
+      IndexedField.<InternalGroup>iterableIntegerBuilder("Member")
+          .build(g -> g.getMembers().stream().map(Account.Id::get).collect(toImmutableList()));
+
+  public static final IndexedField<InternalGroup, Iterable<Integer>>.SearchSpec MEMBER_SPEC =
+      MEMBER_FIELD.integer("member");
+
+  public static final IndexedField<InternalGroup, Iterable<String>> SUBGROUP_FIELD =
+      IndexedField.<InternalGroup>iterableStringBuilder("Subgroup")
+          .build(
               g ->
                   g.getSubgroups().stream().map(AccountGroup.UUID::get).collect(toImmutableList()));
 
+  public static final IndexedField<InternalGroup, Iterable<String>>.SearchSpec SUBGROUP_SPEC =
+      SUBGROUP_FIELD.exact("subgroup");
+
   /** ObjectId of HEAD:refs/groups/<UUID>. */
   public static final FieldDef<InternalGroup, byte[]> REF_STATE =
       storedOnly("ref_state")
diff --git a/java/com/google/gerrit/server/index/group/GroupSchemaDefinitions.java b/java/com/google/gerrit/server/index/group/GroupSchemaDefinitions.java
index 5527345..2fba6ab 100644
--- a/java/com/google/gerrit/server/index/group/GroupSchemaDefinitions.java
+++ b/java/com/google/gerrit/server/index/group/GroupSchemaDefinitions.java
@@ -16,7 +16,9 @@
 
 import static com.google.gerrit.index.SchemaUtil.schema;
 
+import com.google.common.collect.ImmutableList;
 import com.google.gerrit.entities.InternalGroup;
+import com.google.gerrit.index.IndexedField;
 import com.google.gerrit.index.Schema;
 import com.google.gerrit.index.SchemaDefinitions;
 
@@ -31,17 +33,27 @@
   static final Schema<InternalGroup> V5 =
       schema(
           /* version= */ 5,
-          GroupField.CREATED_ON,
-          GroupField.DESCRIPTION,
-          GroupField.ID,
-          GroupField.IS_VISIBLE_TO_ALL,
-          GroupField.MEMBER,
-          GroupField.NAME,
-          GroupField.NAME_PART,
-          GroupField.OWNER_UUID,
-          GroupField.REF_STATE,
-          GroupField.SUBGROUP,
-          GroupField.UUID);
+          ImmutableList.of(GroupField.REF_STATE, GroupField.UUID),
+          ImmutableList.of(
+              GroupField.CREATED_ON_FIELD,
+              GroupField.DESCRIPTION_FIELD,
+              GroupField.ID_FIELD,
+              GroupField.IS_VISIBLE_TO_ALL_FIELD,
+              GroupField.MEMBER_FIELD,
+              GroupField.NAME_FIELD,
+              GroupField.NAME_PART_FIELD,
+              GroupField.OWNER_UUID_FIELD,
+              GroupField.SUBGROUP_FIELD),
+          ImmutableList.<IndexedField<InternalGroup, ?>.SearchSpec>of(
+              GroupField.CREATED_ON_SPEC,
+              GroupField.DESCRIPTION_SPEC,
+              GroupField.ID_FIELD_SPEC,
+              GroupField.IS_VISIBLE_TO_ALL_SPEC,
+              GroupField.MEMBER_SPEC,
+              GroupField.NAME_SPEC,
+              GroupField.NAME_PART_SPEC,
+              GroupField.OWNER_UUID_SPEC,
+              GroupField.SUBGROUP_SPEC));
 
   // Bump Lucene version requires reindexing
   @Deprecated static final Schema<InternalGroup> V6 = schema(V5);
diff --git a/java/com/google/gerrit/server/query/group/GroupPredicates.java b/java/com/google/gerrit/server/query/group/GroupPredicates.java
index 8a2dc8d..8d935d6 100644
--- a/java/com/google/gerrit/server/query/group/GroupPredicates.java
+++ b/java/com/google/gerrit/server/query/group/GroupPredicates.java
@@ -17,7 +17,7 @@
 import com.google.gerrit.entities.Account;
 import com.google.gerrit.entities.AccountGroup;
 import com.google.gerrit.entities.InternalGroup;
-import com.google.gerrit.index.FieldDef;
+import com.google.gerrit.index.SchemaFieldDefs.SchemaField;
 import com.google.gerrit.index.query.IndexPredicate;
 import com.google.gerrit.index.query.Predicate;
 import com.google.gerrit.server.index.group.GroupField;
@@ -26,7 +26,7 @@
 /** Utility class to create predicates for group index queries. */
 public class GroupPredicates {
   public static Predicate<InternalGroup> id(AccountGroup.Id groupId) {
-    return new GroupPredicate(GroupField.ID, groupId.toString());
+    return new GroupPredicate(GroupField.ID_FIELD_SPEC, groupId.toString());
   }
 
   public static Predicate<InternalGroup> uuid(AccountGroup.UUID uuid) {
@@ -35,42 +35,42 @@
 
   public static Predicate<InternalGroup> description(String description) {
     return new GroupPredicate(
-        GroupField.DESCRIPTION, GroupQueryBuilder.FIELD_DESCRIPTION, description);
+        GroupField.DESCRIPTION_SPEC, GroupQueryBuilder.FIELD_DESCRIPTION, description);
   }
 
   public static Predicate<InternalGroup> inname(String name) {
     return new GroupPredicate(
-        GroupField.NAME_PART, GroupQueryBuilder.FIELD_INNAME, name.toLowerCase(Locale.US));
+        GroupField.NAME_PART_SPEC, GroupQueryBuilder.FIELD_INNAME, name.toLowerCase(Locale.US));
   }
 
   public static Predicate<InternalGroup> name(String name) {
-    return new GroupPredicate(GroupField.NAME, name);
+    return new GroupPredicate(GroupField.NAME_SPEC, name);
   }
 
   public static Predicate<InternalGroup> owner(AccountGroup.UUID ownerUuid) {
     return new GroupPredicate(
-        GroupField.OWNER_UUID, GroupQueryBuilder.FIELD_OWNER, ownerUuid.get());
+        GroupField.OWNER_UUID_SPEC, GroupQueryBuilder.FIELD_OWNER, ownerUuid.get());
   }
 
   public static Predicate<InternalGroup> isVisibleToAll() {
-    return new GroupPredicate(GroupField.IS_VISIBLE_TO_ALL, "1");
+    return new GroupPredicate(GroupField.IS_VISIBLE_TO_ALL_SPEC, "1");
   }
 
   public static Predicate<InternalGroup> member(Account.Id memberId) {
-    return new GroupPredicate(GroupField.MEMBER, memberId.toString());
+    return new GroupPredicate(GroupField.MEMBER_SPEC, memberId.toString());
   }
 
   public static Predicate<InternalGroup> subgroup(AccountGroup.UUID subgroupUuid) {
-    return new GroupPredicate(GroupField.SUBGROUP, subgroupUuid.get());
+    return new GroupPredicate(GroupField.SUBGROUP_SPEC, subgroupUuid.get());
   }
 
   /** Predicate that is mapped to a field in the group index. */
   static class GroupPredicate extends IndexPredicate<InternalGroup> {
-    GroupPredicate(FieldDef<InternalGroup, ?> def, String value) {
+    GroupPredicate(SchemaField<InternalGroup, ?> def, String value) {
       super(def, value);
     }
 
-    GroupPredicate(FieldDef<InternalGroup, ?> def, String name, String value) {
+    GroupPredicate(SchemaField<InternalGroup, ?> def, String name, String value) {
       super(def, name, value);
     }
   }
diff --git a/polygerrit-ui/app/api/rest-api.ts b/polygerrit-ui/app/api/rest-api.ts
index 5ec0836..ab33eed 100644
--- a/polygerrit-ui/app/api/rest-api.ts
+++ b/polygerrit-ui/app/api/rest-api.ts
@@ -407,7 +407,6 @@
   cherry_pick_of_change?: NumericChangeId;
   cherry_pick_of_patch_set?: RevisionPatchSetNum;
   contains_git_conflicts?: boolean;
-  internalHost?: string; // TODO(TS): provide an explanation what is its
   submit_requirements?: SubmitRequirementResultInfo[];
   submit_records?: SubmitRecordInfo[];
 }
@@ -1180,3 +1179,19 @@
   status: LabelStatus;
   appliedBy: AccountInfo;
 }
+
+/**
+ * Represent a file in a base64 encoding; GrRestApiInterface returns
+ * it from some methods
+ */
+export declare interface Base64FileContent {
+  content: string | null;
+  type: string | null;
+  ok: true;
+}
+
+export function isBase64FileContent(
+  res: Response | Base64FileContent
+): res is Base64FileContent {
+  return (res as Base64FileContent).ok;
+}
diff --git a/polygerrit-ui/app/elements/admin/gr-access-section/gr-access-section.ts b/polygerrit-ui/app/elements/admin/gr-access-section/gr-access-section.ts
index 4b62710..29f06fd 100644
--- a/polygerrit-ui/app/elements/admin/gr-access-section/gr-access-section.ts
+++ b/polygerrit-ui/app/elements/admin/gr-access-section/gr-access-section.ts
@@ -179,7 +179,7 @@
                 class=${this.section?.id === GLOBAL_NAME ? 'global' : ''}
                 @click=${this.editReference}
               >
-                <gr-icon id="icon" icon="edit"></gr-icon>
+                <gr-icon id="icon" icon="edit" filled small></gr-icon>
               </gr-button>
             </div>
             <iron-input
diff --git a/polygerrit-ui/app/elements/admin/gr-access-section/gr-access-section_test.ts b/polygerrit-ui/app/elements/admin/gr-access-section/gr-access-section_test.ts
index 1048dde..b8cee66 100644
--- a/polygerrit-ui/app/elements/admin/gr-access-section/gr-access-section_test.ts
+++ b/polygerrit-ui/app/elements/admin/gr-access-section/gr-access-section_test.ts
@@ -84,7 +84,7 @@
                   role="button"
                   tabindex="0"
                 >
-                  <gr-icon icon="edit" id="icon"></gr-icon>
+                  <gr-icon icon="edit" id="icon" small filled></gr-icon>
                 </gr-button>
               </div>
               <iron-input class="editRefInput">
diff --git a/polygerrit-ui/app/elements/change-list/gr-change-list-item/gr-change-list-item.ts b/polygerrit-ui/app/elements/change-list/gr-change-list-item/gr-change-list-item.ts
index 8910e27..33129f6 100644
--- a/polygerrit-ui/app/elements/change-list/gr-change-list-item/gr-change-list-item.ts
+++ b/polygerrit-ui/app/elements/change-list/gr-change-list-item/gr-change-list-item.ts
@@ -477,20 +477,16 @@
         ColumnNames.REPO,
         this.visibleChangeTableColumns
       )
-    )
+    ) {
       return;
+    }
 
+    const repo = this.change?.project ?? '';
     return html`
       <td class="cell repo">
-        <a class="fullRepo" href=${this.computeRepoUrl()}>
-          ${this.computeRepoDisplay()}
-        </a>
-        <a
-          class="truncatedRepo"
-          href=${this.computeRepoUrl()}
-          title=${this.computeRepoDisplay()}
-        >
-          ${this.computeTruncatedRepoDisplay()}
+        <a class="fullRepo" href=${this.computeRepoUrl()}> ${repo} </a>
+        <a class="truncatedRepo" href=${this.computeRepoUrl()} title=${repo}>
+          ${truncatePath(repo, 2)}
         </a>
       </td>
     `;
@@ -655,11 +651,7 @@
 
   private computeRepoUrl() {
     if (!this.change) return '';
-    return GerritNav.getUrlForProjectChanges(
-      this.change.project,
-      true,
-      this.change.internalHost
-    );
+    return GerritNav.getUrlForProjectChanges(this.change.project, true);
   }
 
   private computeRepoBranchURL() {
@@ -667,36 +659,13 @@
     return GerritNav.getUrlForBranch(
       this.change.branch,
       this.change.project,
-      undefined,
-      this.change.internalHost
+      undefined
     );
   }
 
   private computeTopicURL() {
     if (!this.change?.topic) return '';
-    return GerritNav.getUrlForTopic(
-      this.change.topic,
-      this.change.internalHost
-    );
-  }
-
-  /**
-   * Computes the display string for the project column. If there is a host
-   * specified in the change detail, the string will be prefixed with it.
-   *
-   * @param truncate whether or not the project name should be
-   * truncated. If this value is truthy, the name will be truncated.
-   *
-   * private but used in test
-   */
-  computeRepoDisplay() {
-    if (!this.change?.project) return '';
-    let str = '';
-    if (this.change.internalHost) {
-      str += this.change.internalHost + '/';
-    }
-    str += this.change.project;
-    return str;
+    return GerritNav.getUrlForTopic(this.change.topic);
   }
 
   private toggleCheckbox() {
@@ -706,19 +675,6 @@
   }
 
   // private but used in test
-  computeTruncatedRepoDisplay() {
-    if (!this.change?.project) {
-      return '';
-    }
-    let str = '';
-    if (this.change.internalHost) {
-      str += this.change.internalHost + '/';
-    }
-    str += truncatePath(this.change.project, 2);
-    return str;
-  }
-
-  // private but used in test
   computeSizeTooltip() {
     if (
       !this.change ||
diff --git a/polygerrit-ui/app/elements/change-list/gr-change-list-item/gr-change-list-item_test.ts b/polygerrit-ui/app/elements/change-list/gr-change-list-item/gr-change-list-item_test.ts
index 50e6c2d..ed8c69f 100644
--- a/polygerrit-ui/app/elements/change-list/gr-change-list-item/gr-change-list-item_test.ts
+++ b/polygerrit-ui/app/elements/change-list/gr-change-list-item/gr-change-list-item_test.ts
@@ -53,7 +53,6 @@
   const account = createAccountWithId();
   const change: ChangeInfo = {
     ...createChange(),
-    internalHost: 'host',
     project: 'a/test/repo' as RepoName,
     topic: 'test-topic' as TopicName,
     branch: 'test-branch' as BranchName,
@@ -335,18 +334,13 @@
     assert.deepEqual(navStub.getUrlForProjectChanges.lastCall.args, [
       change.project,
       true,
-      change.internalHost,
     ]);
     assert.deepEqual(navStub.getUrlForBranch.lastCall.args, [
       change.branch,
       change.project,
       undefined,
-      change.internalHost,
     ]);
-    assert.deepEqual(navStub.getUrlForTopic.lastCall.args, [
-      change.topic,
-      change.internalHost,
-    ]);
+    assert.deepEqual(navStub.getUrlForTopic.lastCall.args, [change.topic!]);
   });
 
   test('clicking item navigates to change', async () => {
@@ -361,16 +355,6 @@
     assert.isTrue(navStub.navigateToChange.calledWithExactly(change));
   });
 
-  test('computeRepoDisplay', () => {
-    element.change = {...change};
-    assert.equal(element.computeRepoDisplay(), 'host/a/test/repo');
-    assert.equal(element.computeTruncatedRepoDisplay(), 'host/…/test/repo');
-    delete change.internalHost;
-    element.change = {...change};
-    assert.equal(element.computeRepoDisplay(), 'a/test/repo');
-    assert.equal(element.computeTruncatedRepoDisplay(), '…/test/repo');
-  });
-
   test('renders', async () => {
     element.showStar = true;
     element.showNumber = true;
diff --git a/polygerrit-ui/app/elements/change-list/gr-change-list-reviewer-flow/gr-change-list-reviewer-flow_test.ts b/polygerrit-ui/app/elements/change-list/gr-change-list-reviewer-flow/gr-change-list-reviewer-flow_test.ts
index 5a4a90c..ef48323 100644
--- a/polygerrit-ui/app/elements/change-list/gr-change-list-reviewer-flow/gr-change-list-reviewer-flow_test.ts
+++ b/polygerrit-ui/app/elements/change-list/gr-change-list-reviewer-flow/gr-change-list-reviewer-flow_test.ts
@@ -891,8 +891,6 @@
       );
 
       assert.deepEqual(reviewerList.accounts[1], {
-        _group: true,
-        _pendingAdd: true,
         confirmed: true,
         id: '5' as GroupId,
         name: 'large-group',
@@ -933,8 +931,6 @@
         getComputedStyle(confirmDialog).getPropertyValue('display') === 'none'
       );
       assert.deepEqual(reviewerList.accounts[1], {
-        _group: true,
-        _pendingAdd: true,
         id: '5' as GroupId,
         name: 'small-group',
       });
diff --git a/polygerrit-ui/app/elements/change/gr-change-metadata/gr-change-metadata.ts b/polygerrit-ui/app/elements/change/gr-change-metadata/gr-change-metadata.ts
index cfb5602..a9f57f5 100644
--- a/polygerrit-ui/app/elements/change/gr-change-metadata/gr-change-metadata.ts
+++ b/polygerrit-ui/app/elements/change/gr-change-metadata/gr-change-metadata.ts
@@ -20,7 +20,6 @@
 import '../gr-submit-requirements/gr-submit-requirements';
 import '../gr-commit-info/gr-commit-info';
 import '../gr-reviewer-list/gr-reviewer-list';
-import '../../shared/gr-account-list/gr-account-list';
 import {GerritNav} from '../../core/gr-navigation/gr-navigation';
 import {
   ChangeStatus,
diff --git a/polygerrit-ui/app/elements/change/gr-confirm-cherrypick-dialog/gr-confirm-cherrypick-dialog.ts b/polygerrit-ui/app/elements/change/gr-confirm-cherrypick-dialog/gr-confirm-cherrypick-dialog.ts
index e6b9058..8bebf58 100644
--- a/polygerrit-ui/app/elements/change/gr-confirm-cherrypick-dialog/gr-confirm-cherrypick-dialog.ts
+++ b/polygerrit-ui/app/elements/change/gr-confirm-cherrypick-dialog/gr-confirm-cherrypick-dialog.ts
@@ -231,34 +231,40 @@
           Cherry Pick Change to Another Branch
         </div>
         <div class="main" slot="main">
-          ${when(this.showCherryPickTopic, () =>
-            this.renderCherrypickTopicLayout()
-          )}
-          <label for="branchInput"> Cherry Pick to branch </label>
-          <gr-autocomplete
-            id="branchInput"
-            .text=${this.branch}
-            .query=${this.query}
-            placeholder="Destination branch"
-            @text-changed=${(e: BindValueChangeEvent) =>
-              (this.branch = e.detail.value as BranchName)}
-          >
-          </gr-autocomplete>
-          ${when(
-            this.invalidBranch,
-            () => html`
-              <span class="error"
-                >Branch name cannot contain space or commas.</span
-              >
-            `
-          )}
-          ${choose(this.cherryPickType, [
-            [
-              CherryPickType.SINGLE_CHANGE,
-              () => this.renderCherrypickSingleChangeInputs(),
-            ],
-            [CherryPickType.TOPIC, () => this.renderCherrypickTopicTable()],
-          ])}
+          <gr-endpoint-decorator name="cherrypick-main">
+            <gr-endpoint-param name="changes" .value=${this.changes}>
+            </gr-endpoint-param>
+            <gr-endpoint-slot name="top"></gr-endpoint-slot>
+            ${when(this.showCherryPickTopic, () =>
+              this.renderCherrypickTopicLayout()
+            )}
+            <label for="branchInput"> Cherry Pick to branch </label>
+            <gr-autocomplete
+              id="branchInput"
+              .text=${this.branch}
+              .query=${this.query}
+              placeholder="Destination branch"
+              @text-changed=${(e: BindValueChangeEvent) =>
+                (this.branch = e.detail.value as BranchName)}
+            >
+            </gr-autocomplete>
+            ${when(
+              this.invalidBranch,
+              () => html`
+                <span class="error"
+                  >Branch name cannot contain space or commas.</span
+                >
+              `
+            )}
+            ${choose(this.cherryPickType, [
+              [
+                CherryPickType.SINGLE_CHANGE,
+                () => this.renderCherrypickSingleChangeInputs(),
+              ],
+              [CherryPickType.TOPIC, () => this.renderCherrypickTopicTable()],
+            ])}
+            <gr-endpoint-slot name="bottom"></gr-endpoint-slot>
+          </gr-endpoint-decorator>
         </div>
       </gr-dialog>
     `;
diff --git a/polygerrit-ui/app/elements/change/gr-confirm-cherrypick-dialog/gr-confirm-cherrypick-dialog_test.ts b/polygerrit-ui/app/elements/change/gr-confirm-cherrypick-dialog/gr-confirm-cherrypick-dialog_test.ts
index fbb6839..7933896 100644
--- a/polygerrit-ui/app/elements/change/gr-confirm-cherrypick-dialog/gr-confirm-cherrypick-dialog_test.ts
+++ b/polygerrit-ui/app/elements/change/gr-confirm-cherrypick-dialog/gr-confirm-cherrypick-dialog_test.ts
@@ -60,29 +60,34 @@
           Cherry Pick Change to Another Branch
         </div>
         <div class="main" slot="main">
-          <label for="branchInput"> Cherry Pick to branch </label>
-          <gr-autocomplete id="branchInput" placeholder="Destination branch">
-          </gr-autocomplete>
-          <label for="baseInput">
-            Provide base commit sha1 for cherry-pick
-          </label>
-          <iron-input>
-            <input
-              id="baseCommitInput"
-              is="iron-input"
-              maxlength="40"
-              placeholder="(optional)"
-            />
-          </iron-input>
-          <label for="messageInput"> Cherry Pick Commit Message </label>
-          <iron-autogrow-textarea
-            aria-disabled="false"
-            autocomplete="on"
-            class="message"
-            id="messageInput"
-            rows="4"
-          >
-          </iron-autogrow-textarea>
+          <gr-endpoint-decorator name="cherrypick-main">
+            <gr-endpoint-param name="changes"> </gr-endpoint-param>
+            <gr-endpoint-slot name="top"> </gr-endpoint-slot>
+            <label for="branchInput"> Cherry Pick to branch </label>
+            <gr-autocomplete id="branchInput" placeholder="Destination branch">
+            </gr-autocomplete>
+            <label for="baseInput">
+              Provide base commit sha1 for cherry-pick
+            </label>
+            <iron-input>
+              <input
+                id="baseCommitInput"
+                is="iron-input"
+                maxlength="40"
+                placeholder="(optional)"
+              />
+            </iron-input>
+            <label for="messageInput"> Cherry Pick Commit Message </label>
+            <iron-autogrow-textarea
+              aria-disabled="false"
+              autocomplete="on"
+              class="message"
+              id="messageInput"
+              rows="4"
+            >
+            </iron-autogrow-textarea>
+            <gr-endpoint-slot name="bottom"></gr-endpoint-slot>
+          </gr-endpoint-decorator>
         </div>
       </gr-dialog>
     `);
diff --git a/polygerrit-ui/app/elements/change/gr-reply-dialog/gr-reply-dialog.ts b/polygerrit-ui/app/elements/change/gr-reply-dialog/gr-reply-dialog.ts
index 731bcd0..ccdcc15 100644
--- a/polygerrit-ui/app/elements/change/gr-reply-dialog/gr-reply-dialog.ts
+++ b/polygerrit-ui/app/elements/change/gr-reply-dialog/gr-reply-dialog.ts
@@ -27,15 +27,14 @@
 } from '../../../constants/constants';
 import {
   accountOrGroupKey,
-  isReviewerOrCC,
-  mapReviewer,
+  isAccountNewlyAdded,
   removeServiceUsers,
+  toReviewInput,
 } from '../../../utils/account-util';
 import {IronA11yAnnouncer} from '@polymer/iron-a11y-announcer/iron-a11y-announcer';
 import {TargetElement} from '../../../api/plugin';
 import {FixIronA11yAnnouncer} from '../../../types/types';
 import {
-  AccountAddition,
   AccountInfoInput,
   AccountInput,
   AccountInputDetail,
@@ -71,6 +70,7 @@
   areSetsEqual,
   assertIsDefined,
   containsAll,
+  difference,
   queryAndAssert,
 } from '../../../utils/common-util';
 import {CommentThread, isUnresolved} from '../../../utils/comment-util';
@@ -108,6 +108,7 @@
 import {customElement, property, state, query} from 'lit/decorators';
 import {subscribe} from '../../lit/subscription-controller';
 import {configModelToken} from '../../../models/config/config-model';
+import {hasHumanReviewer, isOwner} from '../../../utils/change-util';
 
 const STORAGE_DEBOUNCE_INTERVAL_MS = 400;
 
@@ -321,9 +322,6 @@
   @state()
   isResolvedPatchsetLevelComment = true;
 
-  @state()
-  allReviewers: (AccountInfo | GroupInfo)[] = [];
-
   private readonly restApiService: RestApiService =
     getAppContext().restApiService;
 
@@ -493,6 +491,10 @@
       }
       .attention .edit-attention-button gr-icon {
         color: inherit;
+        /* The line-height:26px hack (see below) requires us to do this.
+           Normally the gr-icon would account for a proper positioning
+           within the standard line-height:20px context. */
+        top: 5px;
       }
       .attention a,
       .attention-detail a {
@@ -659,9 +661,6 @@
     if (changedProperties.has('draftCommentThreads')) {
       this.handleHeightChanged();
     }
-    if (changedProperties.has('reviewers')) {
-      this.computeAllReviewers();
-    }
     if (changedProperties.has('sendDisabled')) {
       this.sendDisabledChanged();
     }
@@ -700,7 +699,7 @@
               name="change"
               .value=${this.change}
             ></gr-endpoint-param>
-            <gr-endpoint-param name="reviewers" .value=${this.allReviewers}>
+            <gr-endpoint-param name="reviewers" .value=${[...this.reviewers]}>
             </gr-endpoint-param>
             ${this.renderReviewerList()}
             <gr-endpoint-slot name="below"></gr-endpoint-slot>
@@ -747,6 +746,7 @@
           id="reviewers"
           .accounts=${this.getAccountListCopy(this.reviewers)}
           .change=${this.change}
+          .reviewerState=${ReviewerState.REVIEWER}
           @account-added=${this.accountAdded}
           @accounts-changed=${this.handleReviewersChanged}
           .removableValues=${this.change?.removable_reviewers}
@@ -773,6 +773,8 @@
         <gr-account-list
           id="ccs"
           .accounts=${this.getAccountListCopy(this.ccs)}
+          .change=${this.change}
+          .reviewerState=${ReviewerState.CC}
           @account-added=${this.accountAdded}
           @accounts-changed=${this.handleCcsChanged}
           .removableValues=${this.change?.removable_reviewers}
@@ -969,8 +971,10 @@
                 role="button"
                 tabindex="0"
               >
-                <gr-icon icon="edit" filled></gr-icon>
-                Modify
+                <div>
+                  <gr-icon icon="edit" filled small></gr-icon>
+                  <span>Modify</span>
+                </div>
               </gr-button>
             </gr-tooltip-content>
           </div>
@@ -1047,7 +1051,7 @@
         <div class="peopleList">
           <div class="peopleListLabel">Reviewers</div>
           <div class="peopleListValues">
-            ${this.removeServiceUsers(this.reviewers).map(
+            ${removeServiceUsers(this.reviewers).map(
               account => html`
                 <gr-account-label
                   .account=${account}
@@ -1069,7 +1073,7 @@
             <div class="peopleList">
               <div class="peopleListLabel">CC</div>
               <div class="peopleListValues">
-                ${this.removeServiceUsers(this.ccs).map(
+                ${removeServiceUsers(this.ccs).map(
                   account => html`
                     <gr-account-label
                       .account=${account}
@@ -1281,42 +1285,32 @@
     return isResolvedPatchsetLevelComment ? 'resolved' : 'unresolved';
   }
 
-  computeReviewers(change: ChangeInfo) {
+  computeReviewers() {
     const reviewers: ReviewerInput[] = [];
-    const addToReviewInput = (
-      additions: AccountAddition[],
-      state?: ReviewerState
-    ) => {
-      additions.forEach(addition => {
-        const reviewer = mapReviewer(addition);
-        if (state) reviewer.state = state;
-        reviewers.push(reviewer);
-      });
-    };
-    addToReviewInput(this.reviewersList!.additions(), ReviewerState.REVIEWER);
-    addToReviewInput(this.ccsList!.additions(), ReviewerState.CC);
-    addToReviewInput(
-      this.reviewersList!.removals().filter(
-        r =>
-          isReviewerOrCC(change, r) &&
-          // ignore removal from reviewer request if being added to CC
-          !this.ccsList!.additions().some(
-            account => mapReviewer(account).reviewer === mapReviewer(r).reviewer
-          )
-      ),
-      ReviewerState.REMOVED
+    const reviewerAdditions = this.reviewersList?.additions() ?? [];
+    reviewers.push(
+      ...reviewerAdditions.map(v => toReviewInput(v, ReviewerState.REVIEWER))
     );
-    addToReviewInput(
-      this.ccsList!.removals().filter(
-        r =>
-          isReviewerOrCC(change, r) &&
-          // ignore removal from CC request if being added as reviewer
-          !this.reviewersList!.additions().some(
-            account => mapReviewer(account).reviewer === mapReviewer(r).reviewer
-          )
-      ),
-      ReviewerState.REMOVED
-    );
+
+    const ccAdditions = this.ccsList?.additions() ?? [];
+    reviewers.push(...ccAdditions.map(v => toReviewInput(v, ReviewerState.CC)));
+
+    // ignore removal from reviewer request if being added as CC
+    let removals = difference(
+      this.reviewersList?.removals() ?? [],
+      ccAdditions,
+      (a, b) => accountOrGroupKey(a) === accountOrGroupKey(b)
+    ).map(v => toReviewInput(v, ReviewerState.REMOVED));
+    reviewers.push(...removals);
+
+    // ignore removal from CC request if being added as reviewer
+    removals = difference(
+      this.ccsList?.removals() ?? [],
+      reviewerAdditions,
+      (a, b) => accountOrGroupKey(a) === accountOrGroupKey(b)
+    ).map(v => toReviewInput(v, ReviewerState.REMOVED));
+    reviewers.push(...removals);
+
     return reviewers;
   }
 
@@ -1367,7 +1361,7 @@
     }
 
     assertIsDefined(this.change, 'change');
-    reviewInput.reviewers = this.computeReviewers(this.change);
+    reviewInput.reviewers = this.computeReviewers();
     this.disabled = true;
 
     const errFn = (r?: Response | null) => this.handle400Error(r);
@@ -1422,19 +1416,9 @@
   }
 
   chooseFocusTarget() {
-    // If we are the owner and the reviewers field is empty, focus on that.
-    if (
-      this.account &&
-      this.change &&
-      this.change.owner &&
-      this.account._account_id === this.change.owner._account_id &&
-      (!this.reviewers || this.reviewers?.length === 0)
-    ) {
-      return FocusTarget.REVIEWERS;
-    }
-
-    // Default to BODY.
-    return FocusTarget.BODY;
+    if (!isOwner(this.change, this.account)) return FocusTarget.BODY;
+    if (hasHumanReviewer(this.change)) return FocusTarget.BODY;
+    return FocusTarget.REVIEWERS;
   }
 
   isOwner(account?: AccountInfo, change?: ChangeInfo) {
@@ -1624,7 +1608,11 @@
         );
       this.reviewers
         .filter(r => isAccount(r))
-        .filter(r => r._pendingAdd || (this.canBeStarted && isOwner))
+        .filter(
+          r =>
+            isAccountNewlyAdded(r, ReviewerState.REVIEWER, this.change) ||
+            (this.canBeStarted && isOwner)
+        )
         .filter(notIsReviewerAndHasDraftOrLabel)
         .forEach(r => newAttention.add((r as AccountInfo)._account_id!));
       // Add owner and uploader, if someone else replies.
@@ -1743,10 +1731,6 @@
     return removeServiceUsers(allAccounts.filter(isAccount));
   }
 
-  removeServiceUsers(accounts: AccountInfo[]) {
-    return removeServiceUsers(accounts);
-  }
-
   computeUploader() {
     if (
       !this.change?.current_revision ||
@@ -1816,7 +1800,6 @@
       })
     );
     queryAndAssert<GrTextarea>(this, 'gr-textarea').closeDropdown();
-    this.reviewersList?.clearPendingRemovals();
     this.rebuildReviewerArrays();
   }
 
@@ -2102,10 +2085,6 @@
     }
     this.reporting.reportInteraction('attention-set-actions', {actions});
   }
-
-  computeAllReviewers() {
-    this.allReviewers = [...this.reviewers];
-  }
 }
 
 declare global {
diff --git a/polygerrit-ui/app/elements/change/gr-reply-dialog/gr-reply-dialog_test.ts b/polygerrit-ui/app/elements/change/gr-reply-dialog/gr-reply-dialog_test.ts
index 95cdba91..67190de 100644
--- a/polygerrit-ui/app/elements/change/gr-reply-dialog/gr-reply-dialog_test.ts
+++ b/polygerrit-ui/app/elements/change/gr-reply-dialog/gr-reply-dialog_test.ts
@@ -28,6 +28,7 @@
   createCommentThread,
   createDraft,
   createRevision,
+  createServiceUserWithId,
 } from '../../../test/test-data-generators';
 import {
   pressAndReleaseKeyOn,
@@ -281,8 +282,10 @@
                       role="button"
                       tabindex="0"
                     >
-                      <gr-icon icon="edit" filled></gr-icon>
-                      Modify
+                      <div>
+                        <gr-icon icon="edit" filled small></gr-icon>
+                        <span>Modify</span>
+                      </div>
                     </gr-button>
                   </gr-tooltip-content>
                 </div>
@@ -897,8 +900,8 @@
     await element.updateComplete;
 
     element.reviewers = [
-      {_account_id: 1 as AccountId, _pendingAdd: true},
-      {_account_id: 2 as AccountId, _pendingAdd: true},
+      {_account_id: 1 as AccountId},
+      {_account_id: 2 as AccountId},
     ];
     element.ccs = [];
     element.draftCommentThreads = [];
@@ -927,6 +930,12 @@
       owner: {_account_id: 1 as AccountId},
       status: ChangeStatus.NEW,
       attention_set: {},
+      reviewers: {
+        [ReviewerState.REVIEWER]: [
+          {...createAccountWithId(2)},
+          {...createAccountWithId(3)},
+        ],
+      },
     };
     // let rebuildReviewers triggered by change update finish running
     await element.updateComplete;
@@ -1340,14 +1349,8 @@
     );
 
     // No reviewer/CC should have been added.
-    assert.equal(
-      queryAndAssert<GrAccountList>(element, '#ccs').additions().length,
-      0
-    );
-    assert.equal(
-      queryAndAssert<GrAccountList>(element, '#reviewers').additions().length,
-      0
-    );
+    assert.equal(element.ccsList?.additions().length, 0);
+    assert.equal(element.reviewersList?.additions().length, 0);
 
     // Reopen confirmation dialog.
     observer = overlayObserver('opened');
@@ -1377,17 +1380,11 @@
       isVisible(queryAndAssert(element, 'reviewerConfirmationOverlay'))
     );
     const additions = cc
-      ? queryAndAssert<GrAccountList>(element, '#ccs').additions()
-      : queryAndAssert<GrAccountList>(element, '#reviewers').additions();
+      ? element.ccsList?.additions()
+      : element.reviewersList?.additions();
     assert.deepEqual(additions, [
       {
-        group: {
-          id: 'id' as GroupId,
-          name: 'name' as GroupName,
-          confirmed: true,
-          _group: true,
-          _pendingAdd: true,
-        },
+        name: 'name' as GroupName,
       },
     ]);
 
@@ -1628,28 +1625,22 @@
 
   test('chooseFocusTarget', () => {
     element.account = undefined;
-    assert.strictEqual(element.chooseFocusTarget(), element.FocusTarget.BODY);
+    assert.equal(element.chooseFocusTarget(), element.FocusTarget.BODY);
 
-    element.account = {_account_id: 1 as AccountId};
-    assert.strictEqual(element.chooseFocusTarget(), element.FocusTarget.BODY);
+    element.account = element.change!.owner;
+    assert.equal(element.chooseFocusTarget(), element.FocusTarget.REVIEWERS);
 
-    element.change!.owner = {_account_id: 2 as AccountId};
-    assert.strictEqual(element.chooseFocusTarget(), element.FocusTarget.BODY);
+    element.change!.reviewers.REVIEWER = [createAccountWithId(314)];
+    assert.equal(element.chooseFocusTarget(), element.FocusTarget.BODY);
 
-    element.change!.owner._account_id = 1 as AccountId;
-    assert.strictEqual(
-      element.chooseFocusTarget(),
-      element.FocusTarget.REVIEWERS
-    );
+    element.change!.reviewers.REVIEWER = [createServiceUserWithId(314)];
+    assert.equal(element.chooseFocusTarget(), element.FocusTarget.REVIEWERS);
 
-    element.reviewers = [];
-    assert.strictEqual(
-      element.chooseFocusTarget(),
-      element.FocusTarget.REVIEWERS
-    );
-
-    element.reviewers.push({});
-    assert.strictEqual(element.chooseFocusTarget(), element.FocusTarget.BODY);
+    element.change!.reviewers.REVIEWER = [
+      createAccountWithId(314),
+      createServiceUserWithId(314),
+    ];
+    assert.equal(element.chooseFocusTarget(), element.FocusTarget.BODY);
   });
 
   test('only send labels that have changed', async () => {
@@ -2003,6 +1994,8 @@
       [ReviewerState.REVIEWER]: [{_account_id: reviewer1._account_id}],
     };
 
+    await element.updateComplete;
+
     const mutations: ReviewerInput[] = [];
 
     stubSaveReview((review: ReviewInput) => {
diff --git a/polygerrit-ui/app/elements/change/gr-reviewer-list/gr-reviewer-list.ts b/polygerrit-ui/app/elements/change/gr-reviewer-list/gr-reviewer-list.ts
index 61e16b0..163ec49 100644
--- a/polygerrit-ui/app/elements/change/gr-reviewer-list/gr-reviewer-list.ts
+++ b/polygerrit-ui/app/elements/change/gr-reviewer-list/gr-reviewer-list.ts
@@ -73,15 +73,14 @@
         }
         .addReviewer gr-icon {
           color: inherit;
-          font-size: 18px;
         }
         .controlsContainer {
           display: inline-block;
         }
         gr-button.addReviewer {
-          --gr-button-padding: 1px 0px;
           vertical-align: top;
-          top: 1px;
+          --gr-button-padding: var(--spacing-s);
+          --margin: calc(0px - var(--spacing-s));
         }
         gr-button {
           line-height: var(--line-height-normal);
@@ -117,7 +116,10 @@
               class="addReviewer"
               @click=${this.handleAddTap}
               title=${this.ccsOnly ? 'Add CC' : 'Add reviewer'}
-              ><gr-icon icon="edit" filled></gr-icon>
+            >
+              <div>
+                <gr-icon icon="edit" filled small></gr-icon>
+              </div>
             </gr-button>
           </div>
         </div>
diff --git a/polygerrit-ui/app/elements/change/gr-reviewer-list/gr-reviewer-list_test.ts b/polygerrit-ui/app/elements/change/gr-reviewer-list/gr-reviewer-list_test.ts
index 89bb2fd..9f8aada 100644
--- a/polygerrit-ui/app/elements/change/gr-reviewer-list/gr-reviewer-list_test.ts
+++ b/polygerrit-ui/app/elements/change/gr-reviewer-list/gr-reviewer-list_test.ts
@@ -39,7 +39,9 @@
               tabindex="0"
               title="Add reviewer"
             >
-              <gr-icon icon="edit" filled></gr-icon>
+              <div>
+                <gr-icon icon="edit" filled small></gr-icon>
+              </div>
             </gr-button>
           </div>
         </div>
diff --git a/polygerrit-ui/app/elements/checks/gr-checks-action.ts b/polygerrit-ui/app/elements/checks/gr-checks-action.ts
index 3564ec9..d7373de 100644
--- a/polygerrit-ui/app/elements/checks/gr-checks-action.ts
+++ b/polygerrit-ui/app/elements/checks/gr-checks-action.ts
@@ -6,7 +6,7 @@
 import {LitElement, css, html} from 'lit';
 import {customElement, property} from 'lit/decorators';
 import {Action} from '../../api/checks';
-import {checkRequiredProperty} from '../../utils/common-util';
+import {assertIsDefined} from '../../utils/common-util';
 import {resolve} from '../../models/dependency';
 import {checksModelToken} from '../../models/checks/checks-model';
 @customElement('gr-checks-action')
@@ -25,7 +25,7 @@
 
   override connectedCallback() {
     super.connectedCallback();
-    checkRequiredProperty(this.action, 'action');
+    assertIsDefined(this.action, 'action');
   }
 
   static override get styles() {
diff --git a/polygerrit-ui/app/elements/checks/gr-checks-results.ts b/polygerrit-ui/app/elements/checks/gr-checks-results.ts
index 202c502..edefdd1 100644
--- a/polygerrit-ui/app/elements/checks/gr-checks-results.ts
+++ b/polygerrit-ui/app/elements/checks/gr-checks-results.ts
@@ -33,7 +33,7 @@
   secondaryLinks,
   tooltipForLink,
 } from '../../models/checks/checks-util';
-import {assertIsDefined, check} from '../../utils/common-util';
+import {assertIsDefined, assert} from '../../utils/common-util';
 import {modifierPressed, toggleClass, whenVisible} from '../../utils/dom-util';
 import {durationString} from '../../utils/date-util';
 import {charsOnly} from '../../utils/string-util';
@@ -1201,7 +1201,7 @@
 
   private onPatchsetSelected(e: CustomEvent<{value: string}>) {
     const patchset = Number(e.detail.value);
-    check(!isNaN(patchset), 'selected patchset must be a number');
+    assert(!isNaN(patchset), 'selected patchset must be a number');
     this.getChecksModel().setPatchset(patchset as PatchSetNumber);
   }
 
diff --git a/polygerrit-ui/app/elements/core/gr-navigation/gr-navigation.ts b/polygerrit-ui/app/elements/core/gr-navigation/gr-navigation.ts
index 3942086..63338db 100644
--- a/polygerrit-ui/app/elements/core/gr-navigation/gr-navigation.ts
+++ b/polygerrit-ui/app/elements/core/gr-navigation/gr-navigation.ts
@@ -157,7 +157,6 @@
   // TODO(TS): Define more precise type (enum?)
   statuses?: string[];
   hashtag?: string;
-  host?: string;
   owner?: string;
 }
 
@@ -169,7 +168,6 @@
   patchNum?: RevisionPatchSetNum;
   basePatchNum?: BasePatchSetNum;
   edit?: boolean;
-  host?: string;
   messageHash?: string;
   commentId?: UrlEncodedCommentId;
   forceReload?: boolean;
@@ -456,49 +454,34 @@
 
   /**
    * @param openOnly When true, only search open changes in the project.
-   * @param host The host in which to search.
    */
-  getUrlForProjectChanges(
-    project: RepoName,
-    openOnly?: boolean,
-    host?: string
-  ) {
+  getUrlForProjectChanges(project: RepoName, openOnly?: boolean) {
     return this._getUrlFor({
       view: GerritView.SEARCH,
       project,
       statuses: openOnly ? ['open'] : [],
-      host,
     });
   },
 
   /**
    * @param status The status to search.
-   * @param host The host in which to search.
    */
-  getUrlForBranch(
-    branch: BranchName,
-    project: RepoName,
-    status?: string,
-    host?: string
-  ) {
+  getUrlForBranch(branch: BranchName, project: RepoName, status?: string) {
     return this._getUrlFor({
       view: GerritView.SEARCH,
       branch,
       project,
       statuses: status ? [status] : undefined,
-      host,
     });
   },
 
   /**
    * @param topic The name of the topic.
-   * @param host The host in which to search.
    */
-  getUrlForTopic(topic: TopicName, host?: string) {
+  getUrlForTopic(topic: TopicName) {
     return this._getUrlFor({
       view: GerritView.SEARCH,
       topic,
-      host,
     });
   },
 
@@ -543,7 +526,7 @@
    * @param basePatchNum The string PARENT can be used for none.
    */
   getUrlForChange(
-    change: Pick<ChangeInfo, '_number' | 'project' | 'internalHost'>,
+    change: Pick<ChangeInfo, '_number' | 'project'>,
     options: ChangeUrlParams = {}
   ) {
     let {
@@ -567,7 +550,6 @@
       patchNum,
       basePatchNum,
       edit: isEdit,
-      host: change.internalHost || undefined,
       messageHash,
       forceReload,
       openReplyDialog,
@@ -600,7 +582,7 @@
    *     and re-render everything.
    */
   navigateToChange(
-    change: Pick<ChangeInfo, '_number' | 'project' | 'internalHost'>,
+    change: Pick<ChangeInfo, '_number' | 'project'>,
     options: NavigateToChangeParams = {}
   ) {
     const {
diff --git a/polygerrit-ui/app/elements/diff/gr-apply-fix-dialog/gr-apply-fix-dialog.ts b/polygerrit-ui/app/elements/diff/gr-apply-fix-dialog/gr-apply-fix-dialog.ts
index 5296f13..6e48231 100644
--- a/polygerrit-ui/app/elements/diff/gr-apply-fix-dialog/gr-apply-fix-dialog.ts
+++ b/polygerrit-ui/app/elements/diff/gr-apply-fix-dialog/gr-apply-fix-dialog.ts
@@ -12,15 +12,22 @@
 import {
   NumericChangeId,
   EDIT,
-  FixId,
   FixSuggestionInfo,
   PatchSetNum,
   RobotId,
   BasePatchSetNum,
+  FilePathToDiffInfoMap,
 } from '../../../types/common';
 import {DiffInfo, DiffPreferencesInfo} from '../../../types/diff';
 import {GrOverlay} from '../../shared/gr-overlay/gr-overlay';
-import {isRobot} from '../../../utils/comment-util';
+import {
+  createUserFixSuggestion,
+  getContentInCommentRange,
+  getUserSuggestion,
+  hasUserSuggestion,
+  isRobot,
+  USER_SUGGEST_EDIT_FIX_ID,
+} from '../../../utils/comment-util';
 import {OpenFixPreviewEvent} from '../../../types/events';
 import {getAppContext} from '../../../services/app-context';
 import {fireCloseFixPreview, fireEvent} from '../../../utils/event-util';
@@ -31,6 +38,8 @@
 import {customElement, property, query, state} from 'lit/decorators';
 import {sharedStyles} from '../../../styles/shared-styles';
 import {subscribe} from '../../lit/subscription-controller';
+import {isBase64FileContent} from '../../../api/rest-api';
+import {assertIsDefined} from '../../../utils/common-util';
 
 interface FilePreview {
   filepath: string;
@@ -210,15 +219,32 @@
    * @return Promise that resolves either when all
    * preview diffs are fetched or no fix suggestions in custom event detail.
    */
-  open(e: OpenFixPreviewEvent) {
+  async open(e: OpenFixPreviewEvent) {
     const detail = e.detail;
     const comment = detail.comment;
-    if (!detail.patchNum || !comment || !isRobot(comment)) {
-      return Promise.resolve();
+    if (comment && hasUserSuggestion(comment)) {
+      const replacement = getUserSuggestion(comment);
+      if (!replacement) throw new Error('User suggestion is malformatted');
+      // TODO(milutin): This should belongs into service/model.
+      const file = await this.restApiService.getFileContent(
+        this.changeNum!,
+        comment.path!,
+        comment.patch_set!
+      );
+      assertIsDefined(file, 'file');
+      if (!isBase64FileContent(file))
+        throw new Error('Cannot retrieve file content');
+      assertIsDefined(file.content, 'content');
+      const line = getContentInCommentRange(file.content, comment);
+      this.fixSuggestions = createUserFixSuggestion(comment, line, replacement);
+    } else {
+      if (!detail.patchNum || !comment || !isRobot(comment)) {
+        return Promise.resolve();
+      }
+      this.fixSuggestions = comment.fix_suggestions;
+      this.robotId = comment.robot_id;
     }
     this.patchNum = detail.patchNum;
-    this.fixSuggestions = comment.fix_suggestions;
-    this.robotId = comment.robot_id;
     if (!this.fixSuggestions || !this.fixSuggestions.length) {
       return Promise.resolve();
     }
@@ -233,30 +259,42 @@
     });
   }
 
-  private showSelectedFixSuggestion(fixSuggestion: FixSuggestionInfo) {
+  private async showSelectedFixSuggestion(fixSuggestion: FixSuggestionInfo) {
     this.currentFix = fixSuggestion;
-    return this.fetchFixPreview(fixSuggestion.fix_id);
+    await this.fetchFixPreview(fixSuggestion);
   }
 
-  private fetchFixPreview(fixId: FixId) {
+  private async fetchFixPreview(fixSuggestion: FixSuggestionInfo) {
     if (!this.changeNum || !this.patchNum) {
       return Promise.reject(
         new Error('Both patchNum and changeNum must be set')
       );
     }
-    return this.restApiService
-      .getRobotCommentFixPreview(this.changeNum, this.patchNum, fixId)
-      .then(res => {
-        if (res) {
-          this.currentPreviews = Object.keys(res).map(key => {
-            return {filepath: key, preview: res[key]};
-          });
-        }
-      })
-      .catch(err => {
-        this.close(false);
-        throw err;
-      });
+    let res: FilePathToDiffInfoMap | undefined;
+    try {
+      if (fixSuggestion.fix_id === USER_SUGGEST_EDIT_FIX_ID) {
+        res = await this.restApiService.getFixPreview(
+          this.changeNum,
+          this.patchNum,
+          fixSuggestion.replacements
+        );
+      } else {
+        res = await this.restApiService.getRobotCommentFixPreview(
+          this.changeNum,
+          this.patchNum,
+          fixSuggestion.fix_id
+        );
+      }
+      if (res) {
+        this.currentPreviews = Object.keys(res).map(key => {
+          return {filepath: key, preview: res![key]};
+        });
+      }
+    } catch (e) {
+      this.close(false);
+      throw e;
+    }
+    return res;
   }
 
   private overridePartialDiffPrefs() {
@@ -328,11 +366,20 @@
       throw new Error('Not all required properties are set.');
     }
     this.isApplyFixLoading = true;
-    const res = await this.restApiService.applyFixSuggestion(
-      changeNum,
-      patchNum,
-      this.currentFix.fix_id
-    );
+    let res;
+    if (this.fixSuggestions?.[0].fix_id === USER_SUGGEST_EDIT_FIX_ID) {
+      res = await this.restApiService.applyFixSuggestion(
+        changeNum,
+        patchNum,
+        this.fixSuggestions[0].replacements
+      );
+    } else {
+      res = await this.restApiService.applyRobotFixSuggestion(
+        changeNum,
+        patchNum,
+        this.currentFix.fix_id
+      );
+    }
     if (res && res.ok) {
       GerritNav.navigateToChange(change, {
         patchNum: EDIT,
diff --git a/polygerrit-ui/app/elements/diff/gr-apply-fix-dialog/gr-apply-fix-dialog_test.ts b/polygerrit-ui/app/elements/diff/gr-apply-fix-dialog/gr-apply-fix-dialog_test.ts
index e29731b..8d2b81e 100644
--- a/polygerrit-ui/app/elements/diff/gr-apply-fix-dialog/gr-apply-fix-dialog_test.ts
+++ b/polygerrit-ui/app/elements/diff/gr-apply-fix-dialog/gr-apply-fix-dialog_test.ts
@@ -256,9 +256,9 @@
   });
 
   test('apply fix button should call apply, navigate to change view and fire close', async () => {
-    const applyFixSuggestionStub = stubRestApi('applyFixSuggestion').returns(
-      Promise.resolve(new Response(null, {status: 200}))
-    );
+    const applyRobotFixSuggestionStub = stubRestApi(
+      'applyRobotFixSuggestion'
+    ).returns(Promise.resolve(new Response(null, {status: 200})));
     const navigateToChangeStub = sinon.stub(GerritNav, 'navigateToChange');
     element.currentFix = createFixSuggestionInfo('123');
 
@@ -271,7 +271,7 @@
     await element.handleApplyFix(new CustomEvent('confirm'));
 
     sinon.assert.calledOnceWithExactly(
-      applyFixSuggestionStub,
+      applyRobotFixSuggestionStub,
       element.change!._number,
       2 as PatchSetNum,
       '123'
@@ -296,15 +296,15 @@
   });
 
   test('should not navigate to change view if incorect reponse', async () => {
-    const applyFixSuggestionStub = stubRestApi('applyFixSuggestion').returns(
-      Promise.resolve(new Response(null, {status: 500}))
-    );
+    const applyRobotFixSuggestionStub = stubRestApi(
+      'applyRobotFixSuggestion'
+    ).returns(Promise.resolve(new Response(null, {status: 500})));
     const navigateToChangeStub = sinon.stub(GerritNav, 'navigateToChange');
     element.currentFix = createFixSuggestionInfo('fix_123');
 
     await element.handleApplyFix(new CustomEvent('confirm'));
     sinon.assert.calledWithExactly(
-      applyFixSuggestionStub,
+      applyRobotFixSuggestionStub,
       element.change!._number,
       2 as PatchSetNum,
       'fix_123'
@@ -325,7 +325,7 @@
   });
 
   test('server-error should throw for failed apply call', async () => {
-    stubRestApi('applyFixSuggestion').returns(
+    stubRestApi('applyRobotFixSuggestion').returns(
       Promise.reject(new Error('backend error'))
     );
     const navigateToChangeStub = sinon.stub(GerritNav, 'navigateToChange');
diff --git a/polygerrit-ui/app/elements/gr-app.ts b/polygerrit-ui/app/elements/gr-app.ts
index f63b50e..119cd5a 100644
--- a/polygerrit-ui/app/elements/gr-app.ts
+++ b/polygerrit-ui/app/elements/gr-app.ts
@@ -67,7 +67,8 @@
     }
     if (!this.serviceWorkerInstaller) {
       this.serviceWorkerInstaller = new ServiceWorkerInstaller(
-        appContext.flagsService
+        appContext.flagsService,
+        appContext.userModel
       );
       this.serviceWorkerInstaller.init();
     }
diff --git a/polygerrit-ui/app/elements/shared/gr-account-label/gr-account-label.ts b/polygerrit-ui/app/elements/shared/gr-account-label/gr-account-label.ts
index 5c0c6d6..9e27013 100644
--- a/polygerrit-ui/app/elements/shared/gr-account-label/gr-account-label.ts
+++ b/polygerrit-ui/app/elements/shared/gr-account-label/gr-account-label.ts
@@ -155,11 +155,12 @@
           /* This negates the 4px horizontal padding, which we appreciate as a
          larger click target, but which we don't want to consume space. :-) */
           margin: 0 -4px 0 -4px;
+          --gr-button-padding: 0 var(--spacing-xs);
           vertical-align: top;
         }
         gr-icon.attention {
           color: var(--deemphasized-text-color);
-          font-size: 12px;
+          transform: scaleX(0.8);
         }
         .name {
           display: inline-block;
@@ -235,11 +236,16 @@
                   this.selected,
                   this._selfAccount
                 )}
-                ><gr-icon
-                  icon="label_important"
-                  filled
-                  class="attention"
-                ></gr-icon>
+              >
+                <div>
+                  <gr-icon
+                    icon="label_important"
+                    filled
+                    small
+                    class="attention"
+                  >
+                  </gr-icon>
+                </div>
               </gr-button>
             </gr-tooltip-content>`
           : ''}
diff --git a/polygerrit-ui/app/elements/shared/gr-account-list/gr-account-list.ts b/polygerrit-ui/app/elements/shared/gr-account-list/gr-account-list.ts
index 1fa21e5..c8a2995 100644
--- a/polygerrit-ui/app/elements/shared/gr-account-list/gr-account-list.ts
+++ b/polygerrit-ui/app/elements/shared/gr-account-list/gr-account-list.ts
@@ -15,12 +15,16 @@
   SuggestedReviewerGroupInfo,
   SuggestedReviewerAccountInfo,
   SuggestedReviewerInfo,
+  isGroup,
 } from '../../../types/common';
 import {ReviewerSuggestionsProvider} from '../../../scripts/gr-reviewer-suggestions-provider/gr-reviewer-suggestions-provider';
 import {GrAccountEntry} from '../gr-account-entry/gr-account-entry';
 import {GrAccountChip} from '../gr-account-chip/gr-account-chip';
 import {fire, fireAlert} from '../../../utils/event-util';
-import {accountOrGroupKey} from '../../../utils/account-util';
+import {
+  accountOrGroupKey,
+  isAccountNewlyAdded,
+} from '../../../utils/account-util';
 import {LitElement, css, html, PropertyValues} from 'lit';
 import {customElement, property, query, state} from 'lit/decorators';
 import {sharedStyles} from '../../../styles/shared-styles';
@@ -31,9 +35,10 @@
   GrAutocomplete,
 } from '../gr-autocomplete/gr-autocomplete';
 import {ValueChangedEvent} from '../../../types/events';
-import {queryAndAssert} from '../../../utils/common-util';
+import {difference, queryAndAssert} from '../../../utils/common-util';
 import {PaperInputElement} from '@polymer/paper-input/paper-input';
 import {IronInputElement} from '@polymer/iron-input';
+import {ReviewerState} from '../../../api/rest-api';
 
 const VALID_EMAIL_ALERT = 'Please input a valid email.';
 
@@ -74,37 +79,18 @@
 
 // Internal input type with account info
 export interface AccountInfoInput extends AccountInfo {
-  _group?: boolean;
   _account?: boolean;
-  _pendingAdd?: boolean;
   confirmed?: boolean;
 }
 
 // Internal input type with group info
 export interface GroupInfoInput extends GroupInfo {
-  _group?: boolean;
   _account?: boolean;
-  _pendingAdd?: boolean;
   confirmed?: boolean;
 }
 
-function isAccountInfoInput(x: AccountInput): x is AccountInfoInput {
-  const input = x as AccountInfoInput;
-  return !!input._account || !!input._account_id || !!input.email;
-}
-
-function isGroupInfoInput(x: AccountInput): x is GroupInfoInput {
-  const input = x as GroupInfoInput;
-  return !!input._group || !!input.id;
-}
-
 export type AccountInput = AccountInfoInput | GroupInfoInput;
 
-export interface AccountAddition {
-  account?: AccountInfoInput;
-  group?: GroupInfoInput;
-}
-
 @customElement('gr-account-list')
 export class GrAccountList extends LitElement {
   /**
@@ -129,6 +115,9 @@
   @property({type: Boolean})
   disabled = false;
 
+  @property({type: String})
+  reviewerState?: ReviewerState;
+
   /**
    * Returns suggestions and convert them to list item
    */
@@ -164,8 +153,6 @@
 
   private readonly reporting = getAppContext().reportingService;
 
-  private pendingRemoval: Set<AccountInput> = new Set();
-
   constructor() {
     super();
     this.querySuggestions = input => this.getSuggestions(input);
@@ -190,7 +177,7 @@
       .group {
         --account-label-suffix: ' (group)';
       }
-      .pendingAdd {
+      .newlyAdded {
         font-style: italic;
       }
       .list {
@@ -209,8 +196,12 @@
               .account=${account}
               .change=${this.change}
               class=${classMap({
-                group: !!account._group,
-                pendingAdd: !!account._pendingAdd,
+                group: isGroup(account),
+                newlyAdded: isAccountNewlyAdded(
+                  account,
+                  this.reviewerState,
+                  this.change
+                ),
               })}
               ?removable=${this.computeRemovable(account)}
               @keydown=${this.handleChipKeydown}
@@ -284,8 +275,7 @@
     let group;
     let itemTypeAdded = 'unknown';
     if (isAccountObject(item)) {
-      account = {...item.account, _pendingAdd: true};
-      this.removeFromPendingRemoval(account);
+      account = {...item.account};
       this.accounts.push(account);
       itemTypeAdded = 'account';
     } else if (isSuggestedReviewerGroupInfo(item)) {
@@ -293,9 +283,8 @@
         this.pendingConfirmation = item;
         return;
       }
-      group = {...item.group, _pendingAdd: true, _group: true};
+      group = {...item.group};
       this.accounts.push(group);
-      this.removeFromPendingRemoval(group);
       itemTypeAdded = 'group';
     } else if (this.allowAnyInput) {
       if (!item.includes('@')) {
@@ -305,9 +294,8 @@
         fireAlert(this, VALID_EMAIL_ALERT);
         return false;
       } else {
-        account = {email: item as EmailAddress, _pendingAdd: true};
+        account = {email: item as EmailAddress};
         this.accounts.push(account);
-        this.removeFromPendingRemoval(account);
         itemTypeAdded = 'email';
       }
     }
@@ -323,8 +311,6 @@
     this.accounts.push({
       ...group,
       confirmed: true,
-      _pendingAdd: true,
-      _group: true,
     });
     this.pendingConfirmation = null;
     fire(this, 'accounts-changed', {value: this.accounts});
@@ -332,18 +318,6 @@
   }
 
   // private but used in test
-  computeChipClass(account: AccountInput) {
-    const classes = [];
-    if (account._group) {
-      classes.push('group');
-    }
-    if (account._pendingAdd) {
-      classes.push('pendingAdd');
-    }
-    return classes.join(' ');
-  }
-
-  // private but used in test
   computeRemovable(account: AccountInput) {
     if (this.readonly) {
       return false;
@@ -357,7 +331,7 @@
           return true;
         }
       }
-      return !!account._pendingAdd;
+      return isAccountNewlyAdded(account, this.reviewerState, this.change);
     }
     return true;
   }
@@ -375,7 +349,6 @@
     for (let i = 0; i < this.accounts.length; i++) {
       if (accountOrGroupKey(toRemove) === accountOrGroupKey(this.accounts[i])) {
         this.accounts.splice(i, 1);
-        this.pendingRemoval.add(toRemove);
         this.reporting.reportInteraction(`Remove from ${this.id}`);
         this.requestUpdate();
         fire(this, 'accounts-changed', {value: this.accounts.slice()});
@@ -473,37 +446,19 @@
     return wasSubmitted;
   }
 
-  additions(): AccountAddition[] {
-    return this.accounts
-      .filter(account => account._pendingAdd)
-      .map(account => {
-        if (isGroupInfoInput(account)) {
-          return {group: account};
-        } else if (isAccountInfoInput(account)) {
-          return {account};
-        } else {
-          throw new Error('AccountInput must be either Account or Group.');
-        }
-      });
+  additions(): (AccountInfoInput | GroupInfoInput)[] {
+    if (!this.change) return [];
+    return this.accounts.filter(account =>
+      isAccountNewlyAdded(account, this.reviewerState, this.change)
+    );
   }
 
-  removals(): AccountAddition[] {
-    return Array.from(this.pendingRemoval).map(account => {
-      if (isGroupInfoInput(account)) {
-        return {group: account};
-      } else if (isAccountInfoInput(account)) {
-        return {account};
-      } else {
-        throw new Error('AccountInput must be either Account or Group.');
-      }
-    });
-  }
-
-  private removeFromPendingRemoval(account: AccountInput) {
-    this.pendingRemoval.delete(account);
-  }
-
-  clearPendingRemovals() {
-    this.pendingRemoval.clear();
+  removals(): AccountInfo[] {
+    if (!this.reviewerState) return [];
+    return difference(
+      this.change?.reviewers[this.reviewerState] ?? [],
+      this.accounts,
+      (a, b) => accountOrGroupKey(a) === accountOrGroupKey(b)
+    );
   }
 }
diff --git a/polygerrit-ui/app/elements/shared/gr-account-list/gr-account-list_test.ts b/polygerrit-ui/app/elements/shared/gr-account-list/gr-account-list_test.ts
index 21b9e59..873b6cf 100644
--- a/polygerrit-ui/app/elements/shared/gr-account-list/gr-account-list_test.ts
+++ b/polygerrit-ui/app/elements/shared/gr-account-list/gr-account-list_test.ts
@@ -28,6 +28,8 @@
   GrAutocomplete,
 } from '../gr-autocomplete/gr-autocomplete';
 import {GrAccountEntry} from '../gr-account-entry/gr-account-entry';
+import {createChange} from '../../../test/test-data-generators';
+import {ReviewerState} from '../../../api/rest-api';
 
 const basicFixture = fixtureFromElement('gr-account-list');
 
@@ -65,7 +67,6 @@
     const groupId = `group${++_nextAccountId}`;
     return {
       id: groupId as GroupId,
-      _group: true,
       name: 'abcd' as GroupName,
     };
   };
@@ -94,6 +95,9 @@
 
     element = basicFixture.instantiate();
     element.accounts = [existingAccount1, existingAccount2];
+    element.reviewerState = ReviewerState.REVIEWER;
+    element.change = {...createChange()};
+    element.change.reviewers[ReviewerState.REVIEWER] = [...element.accounts];
     suggestionsProvider = new MockSuggestionsProvider();
     element.suggestionsProvider = suggestionsProvider;
     await element.updateComplete;
@@ -130,18 +134,18 @@
     // Existing accounts are listed.
     let chips = getChips();
     assert.equal(chips.length, 2);
-    assert.isFalse(chips[0].classList.contains('pendingAdd'));
-    assert.isFalse(chips[1].classList.contains('pendingAdd'));
+    assert.isFalse(chips[0].classList.contains('newlyAdded'));
+    assert.isFalse(chips[1].classList.contains('newlyAdded'));
 
-    // New accounts are added to end with pendingAdd class.
+    // New accounts are added to end with newlyAdded class.
     const newAccount = makeAccount();
     handleAdd({account: newAccount, count: 1});
     await element.updateComplete;
     chips = getChips();
     assert.equal(chips.length, 3);
-    assert.isFalse(chips[0].classList.contains('pendingAdd'));
-    assert.isFalse(chips[1].classList.contains('pendingAdd'));
-    assert.isTrue(chips[2].classList.contains('pendingAdd'));
+    assert.isFalse(chips[0].classList.contains('newlyAdded'));
+    assert.isFalse(chips[1].classList.contains('newlyAdded'));
+    assert.isTrue(chips[2].classList.contains('newlyAdded'));
 
     // Removed accounts are taken out of the list.
     element.dispatchEvent(
@@ -154,8 +158,8 @@
     await element.updateComplete;
     chips = getChips();
     assert.equal(chips.length, 2);
-    assert.isFalse(chips[0].classList.contains('pendingAdd'));
-    assert.isTrue(chips[1].classList.contains('pendingAdd'));
+    assert.isFalse(chips[0].classList.contains('newlyAdded'));
+    assert.isTrue(chips[1].classList.contains('newlyAdded'));
 
     // Invalid remove is ignored.
     element.dispatchEvent(
@@ -175,16 +179,16 @@
     await element.updateComplete;
     chips = getChips();
     assert.equal(chips.length, 1);
-    assert.isFalse(chips[0].classList.contains('pendingAdd'));
+    assert.isFalse(chips[0].classList.contains('newlyAdded'));
 
-    // New groups are added to end with pendingAdd and group classes.
+    // New groups are added to end with newlyAdded and group classes.
     const newGroup = makeGroup();
     handleAdd({group: newGroup, confirm: false, count: 1});
     await element.updateComplete;
     chips = getChips();
     assert.equal(chips.length, 2);
     assert.isTrue(chips[1].classList.contains('group'));
-    assert.isTrue(chips[1].classList.contains('pendingAdd'));
+    assert.isTrue(chips[1].classList.contains('newlyAdded'));
 
     // Removed groups are taken out of the list.
     element.dispatchEvent(
@@ -197,7 +201,7 @@
     await element.updateComplete;
     chips = getChips();
     assert.equal(chips.length, 1);
-    assert.isFalse(chips[0].classList.contains('pendingAdd'));
+    assert.isFalse(chips[0].classList.contains('newlyAdded'));
   });
 
   test('getSuggestions uses filter correctly', () => {
@@ -260,20 +264,8 @@
       });
   });
 
-  test('computeChipClass', () => {
-    const account = makeAccount() as AccountInfoInput;
-    assert.equal(element.computeChipClass(account), '');
-    account._pendingAdd = true;
-    assert.equal(element.computeChipClass(account), 'pendingAdd');
-    account._group = true;
-    assert.equal(element.computeChipClass(account), 'group pendingAdd');
-    account._pendingAdd = false;
-    assert.equal(element.computeChipClass(account), 'group');
-  });
-
   test('computeRemovable', async () => {
     const newAccount = makeAccount() as AccountInfoInput;
-    newAccount._pendingAdd = true;
     element.readonly = false;
     element.removableValues = [];
     element.updateComplete;
@@ -320,7 +312,7 @@
     assert.isTrue(element.submitEntryText());
     assert.isTrue(clearStub.called);
     assert.equal(
-      element.additions()[0].account?.email,
+      (element.additions()[0] as AccountInfo)?.email,
       'test@test' as EmailAddress
     );
   });
@@ -335,18 +327,11 @@
 
     assert.deepEqual(element.additions(), [
       {
-        account: {
-          _account_id: newAccount._account_id,
-          _pendingAdd: true,
-        },
+        _account_id: newAccount._account_id,
       },
       {
-        group: {
-          id: newGroup.id,
-          _group: true,
-          _pendingAdd: true,
-          name: 'abcd' as GroupName,
-        },
+        id: newGroup.id,
+        name: 'abcd' as GroupName,
       },
     ]);
   });
@@ -356,7 +341,7 @@
     assert.deepEqual(element.additions(), []);
 
     const group = makeGroup();
-    const reviewer = {
+    const reviewer: RawAccountInput = {
       group,
       count: 10,
       confirm: true,
@@ -370,13 +355,9 @@
     assert.isNull(element.pendingConfirmation);
     assert.deepEqual(element.additions(), [
       {
-        group: {
-          id: group.id,
-          _group: true,
-          _pendingAdd: true,
-          confirmed: true,
-          name: 'abcd' as GroupName,
-        },
+        id: group.id,
+        name: 'abcd' as GroupName,
+        confirmed: true,
       },
     ]);
   });
diff --git a/polygerrit-ui/app/elements/shared/gr-change-status/gr-change-status.ts b/polygerrit-ui/app/elements/shared/gr-change-status/gr-change-status.ts
index 954a606..cbc1428 100644
--- a/polygerrit-ui/app/elements/shared/gr-change-status/gr-change-status.ts
+++ b/polygerrit-ui/app/elements/shared/gr-change-status/gr-change-status.ts
@@ -121,12 +121,9 @@
           padding: 0;
         }
         :host(:not([flat])) .chip,
-        .icon {
+        :host(:not([flat])) .chip gr-icon {
           color: var(--status-text-color);
         }
-        gr-icon {
-          font-size: 18px;
-        }
       `,
     ];
   }
@@ -158,7 +155,7 @@
         <div class="chip" aria-label="Label: ${this.status}">
           ${this.computeStatusString()}
           ${this.showResolveIcon()
-            ? html`<gr-icon icon="edit" filled></gr-icon>`
+            ? html`<gr-icon icon="edit" filled small></gr-icon>`
             : ''}
         </div>
       </a>
diff --git a/polygerrit-ui/app/elements/shared/gr-comment/gr-comment.ts b/polygerrit-ui/app/elements/shared/gr-comment/gr-comment.ts
index 2d6c2b5..456cdff 100644
--- a/polygerrit-ui/app/elements/shared/gr-comment/gr-comment.ts
+++ b/polygerrit-ui/app/elements/shared/gr-comment/gr-comment.ts
@@ -17,7 +17,7 @@
 import '../gr-confirm-delete-comment-dialog/gr-confirm-delete-comment-dialog';
 import '../gr-account-label/gr-account-label';
 import {getAppContext} from '../../../services/app-context';
-import {css, html, LitElement, PropertyValues} from 'lit';
+import {css, html, LitElement, nothing, PropertyValues} from 'lit';
 import {customElement, property, query, state} from 'lit/decorators';
 import {resolve} from '../../../models/dependency';
 import {GerritNav} from '../../core/gr-navigation/gr-navigation';
@@ -34,15 +34,18 @@
 import {
   Comment,
   DraftInfo,
+  getContentInCommentRange,
+  hasUserSuggestion,
   isDraftOrUnsaved,
   isRobot,
   isUnsaved,
+  USER_SUGGESTION_START_PATTERN,
 } from '../../../utils/comment-util';
 import {
   OpenFixPreviewEventDetail,
   ValueChangedEvent,
 } from '../../../types/events';
-import {fire, fireEvent} from '../../../utils/event-util';
+import {fire, fireAlert, fireEvent} from '../../../utils/event-util';
 import {assertIsDefined} from '../../../utils/common-util';
 import {Key, Modifier} from '../../../utils/dom-util';
 import {commentsModelToken} from '../../../models/comments/comments-model';
@@ -51,13 +54,15 @@
 import {ShortcutController} from '../../lit/shortcut-controller';
 import {classMap} from 'lit/directives/class-map';
 import {LineNumber} from '../../../api/diff';
-import {CommentSide} from '../../../constants/constants';
+import {CommentSide, SpecialFilePath} from '../../../constants/constants';
 import {getRandomInt} from '../../../utils/math-util';
 import {Subject} from 'rxjs';
 import {debounceTime} from 'rxjs/operators';
 import {configModelToken} from '../../../models/config/config-model';
 import {changeModelToken} from '../../../models/change/change-model';
 import {Interaction} from '../../../constants/reporting';
+import {KnownExperimentId} from '../../../services/flags/flags';
+import {isBase64FileContent} from '../../../api/rest-api';
 
 const UNSAVED_MESSAGE = 'Unable to save draft';
 
@@ -199,6 +204,8 @@
 
   private readonly reporting = getAppContext().reportingService;
 
+  private readonly flagsService = getAppContext().flagsService;
+
   private readonly getChangeModel = resolve(this, changeModelToken);
 
   // Private but used in tests.
@@ -476,7 +483,7 @@
         <div class="body">
           ${this.renderRobotAuthor()} ${this.renderEditingTextarea()}
           ${this.renderCommentMessage()} ${this.renderHumanActions()}
-          ${this.renderRobotActions()}
+          ${this.renderRobotActions()} ${this.renderSuggestEditActions()}
         </div>
       </div>
       ${this.renderConfirmDialog()}
@@ -702,13 +709,49 @@
     return html`
       <div class="rightActions">
         ${this.autoSaving ? html`.&nbsp;&nbsp;` : ''}
-        ${this.renderDiscardButton()} ${this.renderEditButton()}
+        ${this.renderDiscardButton()} ${this.renderSuggestEditButton()}
+        ${this.renderPreviewSuggestEditButton()} ${this.renderEditButton()}
         ${this.renderCancelButton()} ${this.renderSaveButton()}
         ${this.renderCopyLinkIcon()}
       </div>
     `;
   }
 
+  private renderPreviewSuggestEditButton() {
+    if (!this.flagsService.isEnabled(KnownExperimentId.SUGGEST_EDIT)) {
+      return nothing;
+    }
+    assertIsDefined(this.comment, 'comment');
+    if (!hasUserSuggestion(this.comment)) return nothing;
+    return html`
+      <gr-button
+        link
+        secondary
+        class="action show-fix"
+        ?disabled=${this.saving}
+        @click=${this.handleShowFix}
+      >
+        Preview Fix
+      </gr-button>
+    `;
+  }
+
+  private renderSuggestEditButton() {
+    if (!this.flagsService.isEnabled(KnownExperimentId.SUGGEST_EDIT)) {
+      return nothing;
+    }
+    assertIsDefined(this.comment, 'comment');
+    if (hasUserSuggestion(this.comment)) return nothing;
+    // TODO(milutin): remove this check once suggesting on commit message is
+    // fixed. Currently diff line doesn't match commit message line, because
+    // of metadata in diff, which aren't in content api request.
+    if (this.comment.path === SpecialFilePath.COMMIT_MESSAGE) return nothing;
+    // TODO(milutin): do not show for author/owner
+    return html`<gr-button link class="action" @click=${this.createSuggestEdit}
+      >Suggest Fix</gr-button
+    >`;
+  }
+
   private renderDiscardButton() {
     if (this.editing) return;
     return html`<gr-button
@@ -773,6 +816,22 @@
     `;
   }
 
+  private renderSuggestEditActions() {
+    if (!this.flagsService.isEnabled(KnownExperimentId.SUGGEST_EDIT)) {
+      return nothing;
+    }
+    if (
+      !this.account ||
+      isRobot(this.comment) ||
+      isDraftOrUnsaved(this.comment)
+    ) {
+      return nothing;
+    }
+    return html`
+      <div class="robotActions">${this.renderPreviewSuggestEditButton()}</div>
+    `;
+  }
+
   private renderShowFixButton() {
     if (!(this.comment as RobotCommentInfo)?.fix_suggestions) return;
     return html`
@@ -947,6 +1006,27 @@
     fire(this, 'open-fix-preview', this.getEventPayload());
   }
 
+  async createSuggestEdit() {
+    assertIsDefined(this.comment, 'comment');
+    assertIsDefined(this.changeNum, 'changeNum');
+    // TODO(milutin): showing a toast while the file is being loaded.
+    const file = await this.restApiService.getFileContent(
+      this.changeNum,
+      this.comment.path!,
+      this.comment.patch_set!
+    );
+    if (!file || !isBase64FileContent(file) || !file.content) {
+      fireAlert(this, 'Cannot create suggestion for this file');
+      return;
+    }
+    const line = getContentInCommentRange(file.content, this.comment);
+    if (!line) {
+      fireAlert(this, 'Cannot create suggestion for comment selection');
+      return;
+    }
+    this.messageText += `${USER_SUGGESTION_START_PATTERN}${line}${'\n```'}`;
+  }
+
   // private, but visible for testing
   cancel() {
     assertIsDefined(this.comment, 'comment');
diff --git a/polygerrit-ui/app/elements/shared/gr-copy-clipboard/gr-copy-clipboard.ts b/polygerrit-ui/app/elements/shared/gr-copy-clipboard/gr-copy-clipboard.ts
index 2b62b34..cdd4c4c 100644
--- a/polygerrit-ui/app/elements/shared/gr-copy-clipboard/gr-copy-clipboard.ts
+++ b/polygerrit-ui/app/elements/shared/gr-copy-clipboard/gr-copy-clipboard.ts
@@ -10,8 +10,9 @@
 import {classMap} from 'lit/directives/class-map';
 import {ifDefined} from 'lit/directives/if-defined';
 import {LitElement, css, html} from 'lit';
-import {customElement, property} from 'lit/decorators';
+import {customElement, property, query} from 'lit/decorators';
 import {GrButton} from '../gr-button/gr-button';
+import {GrIcon} from '../gr-icon/gr-icon';
 
 const COPY_TIMEOUT_MS = 1000;
 
@@ -34,6 +35,9 @@
   @property({type: Boolean})
   hideInput = false;
 
+  @query('#icon')
+  iconEl!: GrIcon;
+
   static override get styles() {
     return [
       css`
@@ -55,17 +59,6 @@
           line-height: var(--line-height-mono);
           width: 100%;
         }
-        /*
-         * Typically icons are 20px, which is the normal line-height.
-         * The copy icon is too prominent at 20px, so we choose 16px
-         * here, but add 2x2px padding below, so the entire
-         * component should still fit nicely into a normal inline
-         * layout flow.
-         */
-        #icon {
-          height: 16px;
-          width: 16px;
-        }
         gr-icon {
           color: var(--deemphasized-text-color);
         }
@@ -107,7 +100,7 @@
             @click=${this._copyToClipboard}
             aria-label="Click to copy to clipboard"
           >
-            <gr-icon id="icon" icon="content_copy"></gr-icon>
+            <gr-icon id="icon" icon="content_copy" small></gr-icon>
           </gr-button>
         </gr-tooltip-content>
       </div>
@@ -130,12 +123,8 @@
 
     this.text = queryAndAssert<HTMLInputElement>(this, '#input').value;
     assertIsDefined(this.text, 'text');
-    this.iconEl.innerText = 'check';
+    this.iconEl.icon = 'check';
     navigator.clipboard.writeText(this.text);
-    setTimeout(() => (this.iconEl.innerText = 'content_copy'), COPY_TIMEOUT_MS);
-  }
-
-  private get iconEl(): HTMLSpanElement {
-    return queryAndAssert<HTMLSpanElement>(this, '#icon');
+    setTimeout(() => (this.iconEl.icon = 'content_copy'), COPY_TIMEOUT_MS);
   }
 }
diff --git a/polygerrit-ui/app/elements/shared/gr-copy-clipboard/gr-copy-clipboard_test.ts b/polygerrit-ui/app/elements/shared/gr-copy-clipboard/gr-copy-clipboard_test.ts
index 7b441d3..b10f488 100644
--- a/polygerrit-ui/app/elements/shared/gr-copy-clipboard/gr-copy-clipboard_test.ts
+++ b/polygerrit-ui/app/elements/shared/gr-copy-clipboard/gr-copy-clipboard_test.ts
@@ -43,7 +43,7 @@
             role="button"
             tabindex="0"
           >
-            <gr-icon icon="content_copy" id="icon"></gr-icon>
+            <gr-icon icon="content_copy" id="icon" small></gr-icon>
           </gr-button>
         </gr-tooltip-content>
       </div>
diff --git a/polygerrit-ui/app/elements/shared/gr-editable-content/gr-editable-content.ts b/polygerrit-ui/app/elements/shared/gr-editable-content/gr-editable-content.ts
index ac910ea..5e18afe 100644
--- a/polygerrit-ui/app/elements/shared/gr-editable-content/gr-editable-content.ts
+++ b/polygerrit-ui/app/elements/shared/gr-editable-content/gr-editable-content.ts
@@ -25,6 +25,7 @@
 import {nothing} from 'lit';
 import {classMap} from 'lit/directives/class-map';
 import {when} from 'lit/directives/when';
+import {fontStyles} from '../../../styles/gr-font-styles';
 
 const RESTORED_MESSAGE = 'Content restored from a previous edit.';
 const STORAGE_DEBOUNCE_INTERVAL_MS = 400;
@@ -110,6 +111,7 @@
   static override get styles() {
     return [
       sharedStyles,
+      fontStyles,
       css`
         :host {
           display: block;
@@ -166,7 +168,6 @@
         }
         .show-all-container gr-icon {
           color: inherit;
-          font-size: 18px;
         }
         .cancel-button {
           margin-right: var(--spacing-l);
@@ -175,8 +176,6 @@
           margin-right: var(--spacing-xs);
         }
         gr-button {
-          font-family: var(--font-family);
-          line-height: var(--line-height-normal);
           padding: var(--spacing-xs);
         }
       `,
@@ -233,7 +232,7 @@
       return nothing;
 
     return html`
-      <div class="show-all-container">
+      <div class="show-all-container font-normal">
         ${when(
           this.commitCollapsible && !this.editing,
           () => html`
@@ -242,15 +241,17 @@
               class="show-all-button"
               @click=${this.toggleCommitCollapsed}
             >
-              ${when(
-                !this.commitCollapsed,
-                () => html`<gr-icon icon="expand_less"></gr-icon>`
-              )}
-              ${when(
-                this.commitCollapsed,
-                () => html`<gr-icon icon="expand_more"></gr-icon>`
-              )}
-              ${this.commitCollapsed ? 'Show all' : 'Show less'}
+              <div>
+                ${when(
+                  !this.commitCollapsed,
+                  () => html`<gr-icon icon="expand_less" small></gr-icon>`
+                )}
+                ${when(
+                  this.commitCollapsed,
+                  () => html`<gr-icon icon="expand_more" small></gr-icon>`
+                )}
+                <span>${this.commitCollapsed ? 'Show all' : 'Show less'}</span>
+              </div>
             </gr-button>
             <div class="flex-space"></div>
           `
@@ -263,7 +264,10 @@
               class="edit-commit-message"
               title="Edit commit message"
               @click=${this.handleEditCommitMessage}
-              ><gr-icon icon="edit" filled></gr-icon> Edit</gr-button
+              ><div>
+                <gr-icon icon="edit" filled small></gr-icon>
+                <span>Edit</span>
+              </div></gr-button
             >
           `
         )}
diff --git a/polygerrit-ui/app/elements/shared/gr-editable-content/gr-editable-content_test.ts b/polygerrit-ui/app/elements/shared/gr-editable-content/gr-editable-content_test.ts
index ed09c49..d2663ed 100644
--- a/polygerrit-ui/app/elements/shared/gr-editable-content/gr-editable-content_test.ts
+++ b/polygerrit-ui/app/elements/shared/gr-editable-content/gr-editable-content_test.ts
@@ -27,7 +27,7 @@
       <div class="collapsed viewer">
         <slot> </slot>
       </div>
-      <div class="show-all-container">
+      <div class="show-all-container font-normal">
         <gr-button
           aria-disabled="false"
           class="show-all-button"
@@ -35,8 +35,10 @@
           role="button"
           tabindex="0"
         >
-          <gr-icon icon="expand_more"></gr-icon>
-          Show all
+          <div>
+            <gr-icon icon="expand_more" small></gr-icon>
+            <span>Show all</span>
+          </div>
         </gr-button>
         <div class="flex-space"></div>
         <gr-button
@@ -47,8 +49,10 @@
           tabindex="0"
           title="Edit commit message"
         >
-          <gr-icon icon="edit" filled></gr-icon>
-          Edit
+          <div>
+            <gr-icon icon="edit" filled small></gr-icon>
+            <span>Edit</span>
+          </div>
         </gr-button>
       </div>
       <gr-endpoint-slot name="above-actions"> </gr-endpoint-slot>
diff --git a/polygerrit-ui/app/elements/shared/gr-editable-label/gr-editable-label.ts b/polygerrit-ui/app/elements/shared/gr-editable-label/gr-editable-label.ts
index 231b6fd..19cda0f 100644
--- a/polygerrit-ui/app/elements/shared/gr-editable-label/gr-editable-label.ts
+++ b/polygerrit-ui/app/elements/shared/gr-editable-label/gr-editable-label.ts
@@ -144,10 +144,10 @@
         }
         gr-button gr-icon {
           color: inherit;
-          font-size: 18px;
         }
         gr-button.pencil {
-          --gr-button-padding: 0px 0px;
+          --gr-button-padding: var(--spacing-s);
+          --margin: calc(0px - var(--spacing-s));
         }
       `,
     ];
@@ -188,8 +188,11 @@
         class="pencil ${this.computeLabelClass()}"
         @click=${this.showDropdown}
         title=${this.computeLabel()}
-        ><gr-icon icon="edit" filled></gr-icon
-      ></gr-button>`;
+      >
+        <div>
+          <gr-icon icon="edit" filled small></gr-icon>
+        </div>
+      </gr-button>`;
     } else {
       return html`<label
         class=${this.computeLabelClass()}
diff --git a/polygerrit-ui/app/elements/shared/gr-hovercard-account/gr-hovercard-account.ts b/polygerrit-ui/app/elements/shared/gr-hovercard-account/gr-hovercard-account.ts
index d3b16c8..963c65f 100644
--- a/polygerrit-ui/app/elements/shared/gr-hovercard-account/gr-hovercard-account.ts
+++ b/polygerrit-ui/app/elements/shared/gr-hovercard-account/gr-hovercard-account.ts
@@ -128,9 +128,7 @@
           top: 2px;
         }
         gr-icon.attentionIcon {
-          font-size: 14px;
-          position: relative;
-          top: 3px;
+          transform: scaleX(0.8);
         }
         gr-icon.linkIcon {
           font-size: var(--line-height-normal, 20px);
@@ -270,6 +268,7 @@
           <gr-icon
             icon="label_important"
             filled
+            small
             class="attentionIcon"
           ></gr-icon>
           <span> ${this.computePronoun()} turn to take action. </span>
diff --git a/polygerrit-ui/app/elements/shared/gr-icon/gr-icon.ts b/polygerrit-ui/app/elements/shared/gr-icon/gr-icon.ts
index 00f8ae9..cc6231a 100644
--- a/polygerrit-ui/app/elements/shared/gr-icon/gr-icon.ts
+++ b/polygerrit-ui/app/elements/shared/gr-icon/gr-icon.ts
@@ -21,7 +21,8 @@
  * `icon`.
  *
  * @attr {String} icon - the icon to display
- * @attr {Boolean} filled - whether the icon should be filled.
+ * @attr {Boolean} filled - whether the icon should be filled
+ * @attr {Boolean} small - whether the icon should be smaller than usual
  */
 @customElement('gr-icon')
 export class GrIcon extends LitElement {
@@ -51,6 +52,11 @@
           font-variation-settings: 'FILL' 0;
           vertical-align: top;
         }
+        :host([small]) {
+          font-size: 16px;
+          position: relative;
+          top: 2px;
+        }
         :host([filled]) {
           font-variation-settings: 'FILL' 1;
         }
diff --git a/polygerrit-ui/app/elements/shared/gr-textarea/gr-textarea.ts b/polygerrit-ui/app/elements/shared/gr-textarea/gr-textarea.ts
index 583a5d1..23d0673 100644
--- a/polygerrit-ui/app/elements/shared/gr-textarea/gr-textarea.ts
+++ b/polygerrit-ui/app/elements/shared/gr-textarea/gr-textarea.ts
@@ -119,8 +119,6 @@
 
   private readonly restApiService = getAppContext().restApiService;
 
-  private disableEnterKeyForSelectingSuggestion = false;
-
   private changeNum?: NumericChangeId;
 
   /** Called in disconnectedCallback. */
@@ -297,7 +295,7 @@
 
   // private but used in test
   closeDropdown() {
-    if (this.isMentionsDropdownActive()) {
+    if (this.isMentionsDropdownActive(this.text)) {
       this.mentionsSuggestions?.close();
     } else {
       this.emojiSuggestions?.close();
@@ -350,7 +348,6 @@
     e.stopPropagation();
     this.getVisibleDropdown().cursorUp();
     this.textarea!.textarea.focus();
-    this.disableEnterKeyForSelectingSuggestion = false;
   }
 
   private handleDownKey(e: KeyboardEvent) {
@@ -361,7 +358,6 @@
     e.stopPropagation();
     this.getVisibleDropdown().cursorDown();
     this.textarea!.textarea.focus();
-    this.disableEnterKeyForSelectingSuggestion = false;
   }
 
   private handleTabKey(e: KeyboardEvent) {
@@ -369,7 +365,7 @@
     // has only typed ':'.
     if (
       !this.isDropdownVisible() ||
-      this.disableEnterKeyForSelectingSuggestion
+      (this.isEmojiDropdownActive() && this.currentSearchString === '')
     ) {
       return;
     }
@@ -384,7 +380,7 @@
     // has only typed ':'. Also make sure that shortcuts aren't clobbered.
     if (
       !this.isDropdownVisible() ||
-      this.disableEnterKeyForSelectingSuggestion
+      (this.isEmojiDropdownActive() && this.currentSearchString === '')
     ) {
       this.indent(e);
       return;
@@ -512,9 +508,9 @@
     }
   }
 
-  private isMentionsDropdownActive() {
+  private isMentionsDropdownActive(text: string) {
     return (
-      this.specialCharIndex !== null && this.text[this.specialCharIndex] === '@'
+      this.specialCharIndex !== null && text[this.specialCharIndex] === '@'
     );
   }
 
@@ -548,10 +544,19 @@
 
     const text = e.detail.value ?? '';
 
-    if (!this.isMentionsDropdownActive()) {
-      if (charAtCursor === ':' && this.specialCharIndex === null) {
+    if (this.flagsService.isEnabled(KnownExperimentId.MENTION_USERS)) {
+      // specialCharIndex needs to be assigned before isMentionsDropdownActive
+      // is called
+      if (charAtCursor === '@' && this.specialCharIndex === null) {
         this.specialCharIndex = this.getSpecialCharIndex(text);
       }
+    }
+    if (charAtCursor === ':' && this.specialCharIndex === null) {
+      this.specialCharIndex = this.getSpecialCharIndex(text);
+    }
+
+    // this.text does not contain newly typed character yet
+    if (!this.isMentionsDropdownActive(text)) {
       if (this.specialCharIndex !== null) {
         this.openOrResetDropdown(
           this.emojiSuggestions!,
@@ -566,9 +571,6 @@
 
     if (!this.flagsService.isEnabled(KnownExperimentId.MENTION_USERS)) return;
 
-    if (charAtCursor === '@' && this.specialCharIndex === null) {
-      this.specialCharIndex = this.getSpecialCharIndex(text);
-    }
     if (this.specialCharIndex !== null) {
       this.openOrResetDropdown(
         this.mentionsSuggestions!,
@@ -606,13 +608,11 @@
   determineEmojiSuggestions(suggestionsText: string) {
     if (!suggestionsText.length) {
       this.formatSuggestions(ALL_SUGGESTIONS);
-      this.disableEnterKeyForSelectingSuggestion = true;
     } else {
       const matches = ALL_SUGGESTIONS.filter(suggestion =>
         suggestion.match.includes(suggestionsText)
       ).slice(0, MAX_ITEMS_DROPDOWN);
       this.formatSuggestions(matches);
-      this.disableEnterKeyForSelectingSuggestion = false;
     }
   }
 
diff --git a/polygerrit-ui/app/elements/shared/gr-textarea/gr-textarea_test.ts b/polygerrit-ui/app/elements/shared/gr-textarea/gr-textarea_test.ts
index 0b3bb01..d8b4ad3 100644
--- a/polygerrit-ui/app/elements/shared/gr-textarea/gr-textarea_test.ts
+++ b/polygerrit-ui/app/elements/shared/gr-textarea/gr-textarea_test.ts
@@ -161,6 +161,7 @@
     test('emoji dropdown does not open if mention dropdown is open', async () => {
       const listenerStub = sinon.stub();
       element.addEventListener('bind-value-changed', listenerStub);
+      const resetSpy = sinon.spy(element, 'resetDropdown');
       stubRestApi('getSuggestedAccounts').returns(
         Promise.resolve([
           createAccountWithEmail('abc@google.com'),
@@ -182,6 +183,8 @@
       await waitUntil(() => element.mentions.length > 0);
       await element.updateComplete;
 
+      assert.isFalse(resetSpy.called);
+
       assert.isTrue(element.emojiSuggestions!.isHidden);
       assert.isFalse(element.mentionsSuggestions!.isHidden);
 
diff --git a/polygerrit-ui/app/embed/diff/gr-diff/gr-diff-group.ts b/polygerrit-ui/app/embed/diff/gr-diff/gr-diff-group.ts
index eac76da..5a34ae3 100644
--- a/polygerrit-ui/app/embed/diff/gr-diff/gr-diff-group.ts
+++ b/polygerrit-ui/app/embed/diff/gr-diff/gr-diff-group.ts
@@ -6,7 +6,7 @@
 import {BLANK_LINE, GrDiffLine, GrDiffLineType} from './gr-diff-line';
 import {LineRange, Side} from '../../../api/diff';
 import {LineNumber} from './gr-diff-line';
-import {assertIsDefined, check} from '../../../utils/common-util';
+import {assertIsDefined, assert} from '../../../utils/common-util';
 import {untilRendered} from '../../../utils/dom-util';
 
 export enum GrDiffGroupType {
@@ -267,7 +267,7 @@
           };
         } else {
           assertIsDefined(options.lines);
-          check(options.lines.length > 0, 'diff group must have lines');
+          assert(options.lines.length > 0, 'diff group must have lines');
           for (const line of options.lines) {
             this.addLine(line);
           }
diff --git a/polygerrit-ui/app/services/flags/flags.ts b/polygerrit-ui/app/services/flags/flags.ts
index 54f1a01..c1a63a7 100644
--- a/polygerrit-ui/app/services/flags/flags.ts
+++ b/polygerrit-ui/app/services/flags/flags.ts
@@ -19,6 +19,7 @@
   BULK_ACTIONS = 'UiFeature__bulk_actions_dashboard',
   DIFF_RENDERING_LIT = 'UiFeature__diff_rendering_lit',
   PUSH_NOTIFICATIONS = 'UiFeature__push_notifications',
+  SUGGEST_EDIT = 'UiFeature__suggest_edit',
   RELATED_CHANGES_SUBMITTABILITY = 'UiFeature__related_changes_submittability',
   MENTION_USERS = 'UiFeature__mention_users',
 }
diff --git a/polygerrit-ui/app/services/gr-rest-api/gr-rest-api-impl.ts b/polygerrit-ui/app/services/gr-rest-api/gr-rest-api-impl.ts
index 20493a3..16aa13a 100644
--- a/polygerrit-ui/app/services/gr-rest-api/gr-rest-api-impl.ts
+++ b/polygerrit-ui/app/services/gr-rest-api/gr-rest-api-impl.ts
@@ -119,6 +119,7 @@
   TagInput,
   TopMenuEntryInfo,
   UrlEncodedCommentId,
+  FixReplacementInfo,
 } from '../../types/common';
 import {
   DiffInfo,
@@ -2092,6 +2093,23 @@
     });
   }
 
+  getFixPreview(
+    changeNum: NumericChangeId,
+    patchNum: PatchSetNum,
+    fixReplacementInfos: FixReplacementInfo[]
+  ): Promise<FilePathToDiffInfoMap | undefined> {
+    return this._getChangeURLAndSend({
+      method: HttpMethod.POST,
+      changeNum,
+      patchNum,
+      endpoint: '/fix:preview',
+      reportEndpointAsId: true,
+      headers: {Accept: 'application/json'},
+      parseResponse: true,
+      body: {fix_replacement_infos: fixReplacementInfos},
+    }) as Promise<FilePathToDiffInfoMap | undefined>;
+  }
+
   getRobotCommentFixPreview(
     changeNum: NumericChangeId,
     patchNum: PatchSetNum,
@@ -2108,6 +2126,22 @@
   applyFixSuggestion(
     changeNum: NumericChangeId,
     patchNum: PatchSetNum,
+    fixReplacementInfos: FixReplacementInfo[]
+  ): Promise<Response> {
+    return this._getChangeURLAndSend({
+      method: HttpMethod.POST,
+      changeNum,
+      patchNum,
+      endpoint: '/fix:apply',
+      reportEndpointAsId: true,
+      headers: {Accept: 'application/json'},
+      body: {fix_replacement_infos: fixReplacementInfos},
+    });
+  }
+
+  applyRobotFixSuggestion(
+    changeNum: NumericChangeId,
+    patchNum: PatchSetNum,
     fixId: string
   ): Promise<Response> {
     return this._getChangeURLAndSend({
diff --git a/polygerrit-ui/app/services/gr-rest-api/gr-rest-api.ts b/polygerrit-ui/app/services/gr-rest-api/gr-rest-api.ts
index 14b3ae5..ad574b6 100644
--- a/polygerrit-ui/app/services/gr-rest-api/gr-rest-api.ts
+++ b/polygerrit-ui/app/services/gr-rest-api/gr-rest-api.ts
@@ -41,6 +41,7 @@
   FileNameToFileInfoMap,
   FilePathToDiffInfoMap,
   FixId,
+  FixReplacementInfo,
   GitRef,
   GpgKeyId,
   GpgKeyInfo,
@@ -662,15 +663,45 @@
    */
   awaitPendingDiffDrafts(): Promise<void>;
 
+  /**
+   * Preview Stored Fix
+   * Gets the diffs of all files for a certain {fix-id} associated with apply fix.
+   * https://gerrit-review.googlesource.com/Documentation/rest-api-changes.html#preview-stored-fix
+   */
   getRobotCommentFixPreview(
     changeNum: NumericChangeId,
     patchNum: PatchSetNum,
     fixId: FixId
   ): Promise<FilePathToDiffInfoMap | undefined>;
 
+  /**
+   * Preview Provided fix
+   * Gets the diffs of all files for a provided fix replacements infos
+   * https://gerrit-review.googlesource.com/Documentation/rest-api-changes.html#preview-provided-fix
+   */
+  getFixPreview(
+    changeNum: NumericChangeId,
+    patchNum: PatchSetNum,
+    fixReplacementInfos: FixReplacementInfo[]
+  ): Promise<FilePathToDiffInfoMap | undefined>;
+
+  /**
+   * Apply Provided Fix
+   * https://gerrit-review.googlesource.com/Documentation/rest-api-changes.html#apply-provided-fix
+   */
   applyFixSuggestion(
     changeNum: NumericChangeId,
     patchNum: PatchSetNum,
+    fixReplacementInfos: FixReplacementInfo[]
+  ): Promise<Response>;
+
+  /**
+   * Apply Stored Fix
+   * https://gerrit-review.googlesource.com/Documentation/rest-api-changes.html#apply-stored-fix
+   */
+  applyRobotFixSuggestion(
+    changeNum: NumericChangeId,
+    patchNum: PatchSetNum,
     fixId: string
   ): Promise<Response>;
 
diff --git a/polygerrit-ui/app/services/service-worker-installer.ts b/polygerrit-ui/app/services/service-worker-installer.ts
index 6f889e8..3af79a3 100644
--- a/polygerrit-ui/app/services/service-worker-installer.ts
+++ b/polygerrit-ui/app/services/service-worker-installer.ts
@@ -6,6 +6,8 @@
 
 import {FlagsService, KnownExperimentId} from './flags/flags';
 import {registerServiceWorker} from '../utils/worker-util';
+import {UserModel} from '../models/user/user-model';
+import {AccountDetailInfo} from '../api/rest-api';
 
 /** Type of incoming messages for ServiceWorker. */
 export enum ServiceWorkerMessageType {
@@ -17,7 +19,14 @@
 export class ServiceWorkerInstaller {
   initialized = false;
 
-  constructor(private readonly flagsService: FlagsService) {}
+  account?: AccountDetailInfo;
+
+  constructor(
+    private readonly flagsService: FlagsService,
+    private readonly userModel: UserModel
+  ) {
+    this.userModel.account$.subscribe(acc => (this.account = acc));
+  }
 
   async init() {
     if (this.initialized) return;
@@ -44,6 +53,7 @@
       this.startTriggerTimer();
       navigator.serviceWorker.controller?.postMessage({
         type: ServiceWorkerMessageType.TRIGGER_NOTIFICATIONS,
+        account: this.account,
       });
     }, TRIGGER_NOTIFICATION_UPDATES_MS);
   }
diff --git a/polygerrit-ui/app/services/service-worker-installer_test.ts b/polygerrit-ui/app/services/service-worker-installer_test.ts
index 9de8690..d6b0c02 100644
--- a/polygerrit-ui/app/services/service-worker-installer_test.ts
+++ b/polygerrit-ui/app/services/service-worker-installer_test.ts
@@ -12,8 +12,12 @@
 
   setup(() => {
     const flagsService = getAppContext().flagsService;
+    const userModel = getAppContext().userModel;
     sinon.stub(flagsService, 'isEnabled').returns(true);
-    serviceWorkerInstaller = new ServiceWorkerInstaller(flagsService);
+    serviceWorkerInstaller = new ServiceWorkerInstaller(
+      flagsService,
+      userModel
+    );
   });
 
   test('init', () => {
diff --git a/polygerrit-ui/app/test/mocks/gr-rest-api_mock.ts b/polygerrit-ui/app/test/mocks/gr-rest-api_mock.ts
index 3c4bb62..492bd8d 100644
--- a/polygerrit-ui/app/test/mocks/gr-rest-api_mock.ts
+++ b/polygerrit-ui/app/test/mocks/gr-rest-api_mock.ts
@@ -93,6 +93,9 @@
   applyFixSuggestion(): Promise<Response> {
     return Promise.resolve(new Response());
   },
+  applyRobotFixSuggestion(): Promise<Response> {
+    return Promise.resolve(new Response());
+  },
   awaitPendingDiffDrafts(): Promise<void> {
     return Promise.resolve();
   },
@@ -397,6 +400,9 @@
   getReviewedFiles(): Promise<string[] | undefined> {
     return Promise.resolve([]);
   },
+  getFixPreview(): Promise<FilePathToDiffInfoMap | undefined> {
+    return Promise.resolve({});
+  },
   getRobotCommentFixPreview(): Promise<FilePathToDiffInfoMap | undefined> {
     return Promise.resolve({});
   },
diff --git a/polygerrit-ui/app/test/test-data-generators.ts b/polygerrit-ui/app/test/test-data-generators.ts
index e7e85c2..81ca830 100644
--- a/polygerrit-ui/app/test/test-data-generators.ts
+++ b/polygerrit-ui/app/test/test-data-generators.ts
@@ -72,6 +72,7 @@
 } from '../types/common';
 import {
   AccountsVisibility,
+  AccountTag,
   AppTheme,
   AuthType,
   ChangeStatus,
@@ -188,6 +189,13 @@
   };
 }
 
+export function createServiceUserWithId(id = 5): AccountInfo {
+  return {
+    ...createAccountWithId(id),
+    tags: [AccountTag.SERVICE_USER],
+  };
+}
+
 export function createAccountDetailWithId(id = 5): AccountDetailInfo {
   return {
     _account_id: id as AccountId,
diff --git a/polygerrit-ui/app/tsconfig.json b/polygerrit-ui/app/tsconfig.json
index b799e58..8101b22 100644
--- a/polygerrit-ui/app/tsconfig.json
+++ b/polygerrit-ui/app/tsconfig.json
@@ -46,7 +46,7 @@
     "lib": [
       "dom",
       "dom.iterable",
-      "es2019",
+      "es2020",
       "webworker"
     ],
 
diff --git a/polygerrit-ui/app/types/common.ts b/polygerrit-ui/app/types/common.ts
index 77b0305..0e05828 100644
--- a/polygerrit-ui/app/types/common.ts
+++ b/polygerrit-ui/app/types/common.ts
@@ -115,6 +115,7 @@
   WebLinkInfo,
   isDetailedLabelInfo,
   isQuickLabelInfo,
+  Base64FileContent,
 } from '../api/rest-api';
 import {DiffInfo, IgnoreWhitespaceType} from './diff';
 
@@ -128,6 +129,7 @@
   ApprovalInfo,
   AuthInfo,
   AvatarInfo,
+  Base64FileContent,
   BasePatchSetNum,
   BranchName,
   BrandType,
@@ -923,16 +925,6 @@
 }
 
 /**
- * Represent a file in a base64 encoding; GrRestApiInterface returns it from some
- * methods
- */
-export interface Base64FileContent {
-  content: string | null;
-  type: string | null;
-  ok: true;
-}
-
-/**
  * The WatchedProjectsInfo entity contains information about a project watch for a user
  * https://gerrit-review.googlesource.com/Documentation/rest-api-accounts.html#project-watch-info
  */
diff --git a/polygerrit-ui/app/utils/account-util.ts b/polygerrit-ui/app/utils/account-util.ts
index de2c20b..012dc1c 100644
--- a/polygerrit-ui/app/utils/account-util.ts
+++ b/polygerrit-ui/app/utils/account-util.ts
@@ -19,13 +19,13 @@
 } from '../types/common';
 import {AccountTag, ReviewerState} from '../constants/constants';
 import {assertNever, hasOwnProperty} from './common-util';
-import {AccountAddition} from '../elements/shared/gr-account-list/gr-account-list';
 import {getDisplayName} from './display-name-util';
 import {getApprovalInfo} from './label-util';
 import {RestApiService} from '../services/gr-rest-api/gr-rest-api';
 
 export const ACCOUNT_TEMPLATE_REGEX = '<GERRIT_ACCOUNT_(\\d+)>';
 const SUGGESTIONS_LIMIT = 15;
+// https://html.spec.whatwg.org/multipage/input.html#valid-e-mail-address
 export const MENTIONS_REGEX =
   /(?:^|\s)@([a-zA-Z0-9.!#$%&'*+=?^_`{|}~-]+@[a-zA-Z0-9](?:[a-zA-Z0-9-]{0,61}[a-zA-Z0-9])?(?:\.[a-zA-Z0-9](?:[a-zA-Z0-9-]{0,61}[a-zA-Z0-9])?)*)(?:\s+|$)/g;
 
@@ -35,30 +35,6 @@
   throw new Error('Account has neither _account_id nor email.');
 }
 
-export function mapReviewer(addition: AccountAddition): ReviewerInput {
-  if (addition.account) {
-    return {reviewer: accountKey(addition.account)};
-  }
-  if (addition.group) {
-    const reviewer = decodeURIComponent(addition.group.id) as GroupId;
-    const confirmed = addition.group.confirmed;
-    return {reviewer, confirmed};
-  }
-  throw new Error('Reviewer must be either an account or a group.');
-}
-
-export function isReviewerOrCC(
-  change: ChangeInfo,
-  reviewerAddition: AccountAddition
-): boolean {
-  const reviewers = [
-    ...(change.reviewers[ReviewerState.CC] ?? []),
-    ...(change.reviewers[ReviewerState.REVIEWER] ?? []),
-  ];
-  const reviewer = mapReviewer(reviewerAddition);
-  return reviewers.some(r => accountOrGroupKey(r) === reviewer.reviewer);
-}
-
 export function isServiceUser(account?: AccountInfo): boolean {
   return !!account?.tags?.includes(AccountTag.SERVICE_USER);
 }
@@ -81,6 +57,18 @@
   assertNever(entry, 'entry must be account or group');
 }
 
+export function isAccountNewlyAdded(
+  account: AccountInfo | GroupInfo,
+  state?: ReviewerState,
+  change?: ChangeInfo
+) {
+  if (!change || !state) return false;
+  const accounts = [...(change.reviewers[state] ?? [])];
+  return !accounts.some(
+    a => accountOrGroupKey(a) === accountOrGroupKey(account)
+  );
+}
+
 export function uniqueDefinedAvatar(
   account: AccountInfo,
   index: number,
@@ -213,5 +201,26 @@
  */
 export function extractMentionedEmails(text?: string): EmailAddress[] {
   if (!text) return [];
-  return [...text.matchAll(MENTIONS_REGEX)].map(m => m[1] as EmailAddress);
+  let match;
+  const emails = [];
+  while ((match = MENTIONS_REGEX.exec(text))) {
+    emails.push(match[1] as EmailAddress);
+  }
+  return emails;
+}
+
+export function toReviewInput(
+  account: AccountInfo | GroupInfo,
+  state: ReviewerState
+): ReviewerInput {
+  if (isAccount(account)) {
+    return {
+      reviewer: accountKey(account),
+      state,
+    };
+  } else if (isGroup(account)) {
+    const reviewer = decodeURIComponent(account.id) as GroupId;
+    return {reviewer, state};
+  }
+  throw new Error('Must be either an account or a group.');
 }
diff --git a/polygerrit-ui/app/utils/account-util_test.ts b/polygerrit-ui/app/utils/account-util_test.ts
index 5c58d5a..68fa386 100644
--- a/polygerrit-ui/app/utils/account-util_test.ts
+++ b/polygerrit-ui/app/utils/account-util_test.ts
@@ -81,6 +81,9 @@
     text = '@abcgoogle.com';
     assert.deepEqual(extractMentionedEmails(text), []);
 
+    text = '@abc@googlecom';
+    assert.deepEqual(extractMentionedEmails(text), ['abc@googlecom']);
+
     // with newline before email
     text = '\n\n\n random text  \n\n@abc@google.com';
     assert.deepEqual(extractMentionedEmails(text), ['abc@google.com']);
diff --git a/polygerrit-ui/app/utils/change-util.ts b/polygerrit-ui/app/utils/change-util.ts
index d6d2f7d..cf0ff53 100644
--- a/polygerrit-ui/app/utils/change-util.ts
+++ b/polygerrit-ui/app/utils/change-util.ts
@@ -14,6 +14,7 @@
 } from '../types/common';
 import {ParsedChangeInfo} from '../types/types';
 import {ChangeStates} from '../elements/shared/gr-change-status/gr-change-status';
+import {isServiceUser} from './account-util';
 
 // This can be wrong! See WARNING above
 interface ChangeStatusesOptions {
@@ -249,6 +250,11 @@
   );
 }
 
+export function hasHumanReviewer(change?: ChangeInfo): boolean {
+  const reviewers = change?.reviewers.REVIEWER ?? [];
+  return reviewers.some(r => !isServiceUser(r));
+}
+
 export function isRemovableReviewer(
   change?: ChangeInfo,
   reviewer?: AccountInfo
diff --git a/polygerrit-ui/app/utils/comment-util.ts b/polygerrit-ui/app/utils/comment-util.ts
index c5cbe64..c187a50 100644
--- a/polygerrit-ui/app/utils/comment-util.ts
+++ b/polygerrit-ui/app/utils/comment-util.ts
@@ -20,6 +20,8 @@
   AccountDetailInfo,
   ChangeMessageInfo,
   VotingRangeInfo,
+  FixSuggestionInfo,
+  FixId,
 } from '../types/common';
 import {CommentSide, SpecialFilePath} from '../constants/constants';
 import {parseDate} from './date-util';
@@ -492,3 +494,55 @@
     unsaved: isUnsaved(comment),
   };
 }
+
+export const USER_SUGGESTION_START_PATTERN = '```suggestion\n';
+export const USER_SUGGEST_EDIT_FIX_ID = 'user_suggestion' as FixId;
+
+export function hasUserSuggestion(comment: Comment) {
+  return comment.message?.includes(USER_SUGGESTION_START_PATTERN) ?? false;
+}
+
+export function getUserSuggestion(comment: Comment) {
+  if (!comment.message) return;
+  const start =
+    comment.message.indexOf(USER_SUGGESTION_START_PATTERN) +
+    USER_SUGGESTION_START_PATTERN.length;
+  const end = comment.message.indexOf('\n```', start);
+  return comment.message.substring(start, end);
+}
+
+/**
+ * Currently it works only on 1 line.
+ * TODO(milutin): Extend for multiline comments
+ */
+export function getContentInCommentRange(
+  fileContent: string,
+  comment: Comment
+) {
+  return fileContent.split('\n')[comment.line! - 1];
+}
+
+export function createUserFixSuggestion(
+  comment: Comment,
+  line: string,
+  replacement: string
+): FixSuggestionInfo[] {
+  return [
+    {
+      fix_id: USER_SUGGEST_EDIT_FIX_ID,
+      description: 'User suggestion',
+      replacements: [
+        {
+          path: comment.path!,
+          range: {
+            start_line: comment.line!,
+            start_character: 0,
+            end_line: comment.line!,
+            end_character: line.length,
+          },
+          replacement,
+        },
+      ],
+    },
+  ];
+}
diff --git a/polygerrit-ui/app/utils/comment-util_test.ts b/polygerrit-ui/app/utils/comment-util_test.ts
index bb9c455..dd57042 100644
--- a/polygerrit-ui/app/utils/comment-util_test.ts
+++ b/polygerrit-ui/app/utils/comment-util_test.ts
@@ -9,6 +9,12 @@
   getPatchRangeForCommentUrl,
   createCommentThreads,
   sortComments,
+  USER_SUGGESTION_START_PATTERN,
+  hasUserSuggestion,
+  getUserSuggestion,
+  getContentInCommentRange,
+  createUserFixSuggestion,
+  USER_SUGGEST_EDIT_FIX_ID,
 } from './comment-util';
 import {createComment, createCommentThread} from '../test/test-data-generators';
 import {CommentSide} from '../constants/constants';
@@ -223,4 +229,58 @@
       assert.equal(createCommentThreads(comments).length, 2);
     });
   });
+
+  test('hasUserSuggestion', () => {
+    const comment = {
+      ...createComment(),
+      message: `${USER_SUGGESTION_START_PATTERN}${'test'}${'\n```'}`,
+    };
+    assert.isTrue(hasUserSuggestion(comment));
+  });
+
+  test('getUserSuggestion', () => {
+    const suggestion = 'test';
+    const comment = {
+      ...createComment(),
+      message: `${USER_SUGGESTION_START_PATTERN}${suggestion}${'\n```'}`,
+    };
+    assert.equal(getUserSuggestion(comment), suggestion);
+  });
+
+  test('getContentInCommentRange', () => {
+    const comment = {
+      ...createComment(),
+      line: 1,
+    };
+    const content = 'line1\nline2\nline3';
+    assert.equal(getContentInCommentRange(content, comment), 'line1');
+  });
+
+  test('createUserFixSuggestion', () => {
+    const comment = {
+      ...createComment(),
+      line: 1,
+      path: 'abc.txt',
+    };
+    const line = 'lane1';
+    const replacement = 'line1';
+    assert.deepEqual(createUserFixSuggestion(comment, line, replacement), [
+      {
+        fix_id: USER_SUGGEST_EDIT_FIX_ID,
+        description: 'User suggestion',
+        replacements: [
+          {
+            path: 'abc.txt',
+            range: {
+              start_line: 1,
+              start_character: 0,
+              end_line: 1,
+              end_character: line.length,
+            },
+            replacement,
+          },
+        ],
+      },
+    ]);
+  });
 });
diff --git a/polygerrit-ui/app/utils/common-util.ts b/polygerrit-ui/app/utils/common-util.ts
index fe86d91..0bae49a 100644
--- a/polygerrit-ui/app/utils/common-util.ts
+++ b/polygerrit-ui/app/utils/common-util.ts
@@ -38,7 +38,7 @@
 /**
  * Throws an error with the provided error message if the condition is false.
  */
-export function check(
+export function assert(
   condition: boolean,
   errorMessage: string
 ): asserts condition {
@@ -48,28 +48,6 @@
 /**
  * Throws an error if the property is not defined.
  */
-export function checkProperty(
-  condition: boolean,
-  propertyName: string
-): asserts condition {
-  check(condition, `missing required property '${propertyName}'`);
-}
-
-/**
- * Throws an error if the property is not defined.
- */
-export function checkRequiredProperty<T>(
-  property: T,
-  propertyName: string
-): asserts property is NonNullable<T> {
-  if (property === undefined || property === null) {
-    throw new Error(`Required property '${propertyName}' not set.`);
-  }
-}
-
-/**
- * Throws an error if the property is not defined.
- */
 export function assertIsDefined<T>(
   val: T,
   variableName = 'variable'
@@ -168,3 +146,14 @@
     result.filter(t => array.find(u => compareBy(t, u)))
   );
 }
+
+/**
+ * Returns the elements that are present in A but not present in B.
+ */
+export function difference<T>(
+  a: T[],
+  b: T[],
+  compareBy: (t: T, u: T) => boolean = (t, u) => t === u
+): T[] {
+  return a.filter(aVal => !b.some(bVal => compareBy(aVal, bVal)));
+}
diff --git a/polygerrit-ui/app/utils/common-util_test.ts b/polygerrit-ui/app/utils/common-util_test.ts
index e07401b..c9ba060 100644
--- a/polygerrit-ui/app/utils/common-util_test.ts
+++ b/polygerrit-ui/app/utils/common-util_test.ts
@@ -9,6 +9,7 @@
   areSetsEqual,
   containsAll,
   intersection,
+  difference,
 } from './common-util';
 
 suite('common-util tests', () => {
@@ -88,4 +89,11 @@
       [foo1]
     );
   });
+
+  test('difference', () => {
+    assert.deepEqual(difference([1, 2, 3], []), [1, 2, 3]);
+    assert.deepEqual(difference([1, 2, 3], [2, 3, 4]), [1]);
+    assert.deepEqual(difference([1, 2, 3], [1, 2, 3]), []);
+    assert.deepEqual(difference([1, 2, 3], [4, 5, 6]), [1, 2, 3]);
+  });
 });
diff --git a/polygerrit-ui/app/utils/patch-set-util.ts b/polygerrit-ui/app/utils/patch-set-util.ts
index f8ba4c3..515f2e7 100644
--- a/polygerrit-ui/app/utils/patch-set-util.ts
+++ b/polygerrit-ui/app/utils/patch-set-util.ts
@@ -9,7 +9,7 @@
   RevisionPatchSetNum,
 } from '../types/common';
 import {EditRevisionInfo, ParsedChangeInfo} from '../types/types';
-import {check} from './common-util';
+import {assert} from './common-util';
 
 /**
  * @license
@@ -261,7 +261,7 @@
   if (latest === EDIT) {
     latest = allPatchSets[1].num;
   }
-  check(isNumber(latest), 'Latest patchset cannot be EDIT or PARENT.');
+  assert(isNumber(latest), 'Latest patchset cannot be EDIT or PARENT.');
   return latest;
 }
 
diff --git a/polygerrit-ui/app/utils/service-worker-util.ts b/polygerrit-ui/app/utils/service-worker-util.ts
new file mode 100644
index 0000000..3cf0dce
--- /dev/null
+++ b/polygerrit-ui/app/utils/service-worker-util.ts
@@ -0,0 +1,29 @@
+/**
+ * @license
+ * Copyright 2022 Google LLC
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+import {AccountDetailInfo} from '../api/rest-api';
+import {ParsedChangeInfo} from '../types/types';
+import {parseDate} from './date-util';
+
+/**
+ * Filter changes that had change in attention set after last round
+ * of notifications. Filter out changes we already notified about.
+ */
+export function filterAttentionChangesAfter(
+  changes: ParsedChangeInfo[],
+  account: AccountDetailInfo,
+  latestUpdateTimestampMs?: number
+) {
+  if (!latestUpdateTimestampMs) return changes;
+  return changes.filter(change => {
+    const attention_set = change.attention_set![account._account_id!];
+    if (!attention_set.last_update) return false;
+    const lastUpdateTimestampMs = parseDate(
+      attention_set.last_update
+    ).valueOf();
+    return latestUpdateTimestampMs < lastUpdateTimestampMs;
+  });
+}
diff --git a/polygerrit-ui/app/utils/service-worker-util_test.ts b/polygerrit-ui/app/utils/service-worker-util_test.ts
new file mode 100644
index 0000000..0caea3b
--- /dev/null
+++ b/polygerrit-ui/app/utils/service-worker-util_test.ts
@@ -0,0 +1,48 @@
+/**
+ * @license
+ * Copyright 2017 Google LLC
+ * SPDX-License-Identifier: Apache-2.0
+ */
+import {Timestamp} from '../api/rest-api';
+import '../test/common-test-setup-karma';
+import {
+  createAccountDetailWithId,
+  createParsedChange,
+} from '../test/test-data-generators';
+import {ParsedChangeInfo} from '../types/types';
+import {parseDate} from './date-util';
+import {filterAttentionChangesAfter} from './service-worker-util';
+
+suite('service worker util tests', () => {
+  test('filterAttentionChangesAfter', () => {
+    const account = createAccountDetailWithId();
+    const changeBefore: ParsedChangeInfo = {
+      ...createParsedChange(),
+      attention_set: {
+        [`${account._account_id}`]: {
+          account,
+          last_update: '2016-01-12 20:24:49.000000000' as Timestamp,
+        },
+      },
+    };
+    const changeAfter: ParsedChangeInfo = {
+      ...createParsedChange(),
+      attention_set: {
+        [`${account._account_id}`]: {
+          account,
+          last_update: '2016-01-12 20:24:51.000000000' as Timestamp,
+        },
+      },
+    };
+    const changes = [changeBefore, changeAfter];
+
+    const filteredChanges = filterAttentionChangesAfter(
+      changes,
+      account,
+      parseDate('2016-01-12 20:24:50.000000000' as Timestamp).valueOf()
+    );
+
+    assert.equal(filteredChanges.length, 1);
+    assert.equal(filteredChanges[0], changeAfter);
+  });
+});
diff --git a/polygerrit-ui/app/workers/service-worker-class.ts b/polygerrit-ui/app/workers/service-worker-class.ts
new file mode 100644
index 0000000..966b6b0
--- /dev/null
+++ b/polygerrit-ui/app/workers/service-worker-class.ts
@@ -0,0 +1,56 @@
+/**
+ * @license
+ * Copyright 2022 Google LLC
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+import {ParsedChangeInfo} from '../types/types';
+import {getReason} from '../utils/attention-set-util';
+import {readResponsePayload} from '../elements/shared/gr-rest-api-interface/gr-rest-apis/gr-rest-api-helper';
+import {filterAttentionChangesAfter} from '../utils/service-worker-util';
+import {AccountDetailInfo} from '../api/rest-api';
+import {TRIGGER_NOTIFICATION_UPDATES_MS} from '../services/service-worker-installer';
+
+export class ServiceWorker {
+  constructor(private ctx: ServiceWorkerGlobalScope) {}
+
+  latestUpdateTimestampMs?: number;
+
+  showNotification(change: ParsedChangeInfo, account: AccountDetailInfo) {
+    const body = getReason(undefined, account, change);
+    // TODO(milutin): Implement event.action that
+    // focus on firstWindowClient and open change there.
+    // TODO(milutin): Add gerrit host icon
+    this.ctx.registration.showNotification(change.subject, {body});
+  }
+
+  async getChangesToNotify(account: AccountDetailInfo) {
+    // We throttle polling, since there can be many clients triggerring
+    // always only one service worker.
+    if (this.latestUpdateTimestampMs) {
+      const durationFromLatestUpdateMS =
+        Date.now() - this.latestUpdateTimestampMs;
+      if (durationFromLatestUpdateMS < TRIGGER_NOTIFICATION_UPDATES_MS) {
+        return [];
+      }
+    }
+    const changes = await this.getLatestAttentionSetChanges();
+    const latestAttentionChanges = filterAttentionChangesAfter(
+      changes,
+      account,
+      this.latestUpdateTimestampMs
+    );
+    this.latestUpdateTimestampMs = Date.now();
+    return latestAttentionChanges;
+  }
+
+  async getLatestAttentionSetChanges(): Promise<ParsedChangeInfo[]> {
+    // TODO(milutin): Implement more generic query builder
+    const response = await fetch(
+      '/changes/?O=1000081&S=0&n=25&q=attention%3Aself'
+    );
+    const payload = await readResponsePayload(response);
+    const changes = payload.parsed as unknown as ParsedChangeInfo[] | undefined;
+    return changes ?? [];
+  }
+}
diff --git a/polygerrit-ui/app/workers/service-worker-class_test.ts b/polygerrit-ui/app/workers/service-worker-class_test.ts
new file mode 100644
index 0000000..ecfef5e
--- /dev/null
+++ b/polygerrit-ui/app/workers/service-worker-class_test.ts
@@ -0,0 +1,50 @@
+/**
+ * @license
+ * Copyright 2022 Google LLC
+ * SPDX-License-Identifier: Apache-2.0
+ */
+import {Timestamp} from '../api/rest-api';
+import '../test/common-test-setup-karma';
+import {
+  createAccountDetailWithId,
+  createParsedChange,
+} from '../test/test-data-generators';
+import {ParsedChangeInfo} from '../types/types';
+import {parseDate} from '../utils/date-util';
+import {ServiceWorker} from './service-worker-class';
+
+suite('service worker class tests', () => {
+  let serviceWorker: ServiceWorker;
+
+  setup(() => {
+    const moctCtx = {
+      registration: {
+        showNotification: () => {},
+      },
+    } as {} as ServiceWorkerGlobalScope;
+    serviceWorker = new ServiceWorker(moctCtx);
+  });
+
+  test('notify about attention in t2 when time is t3', async () => {
+    const t1 = parseDate('2016-01-12 20:20:00' as Timestamp).getTime();
+    const t2 = '2016-01-12 20:30:00' as Timestamp;
+    const t3 = parseDate('2016-01-12 20:40:00' as Timestamp).getTime();
+    serviceWorker.latestUpdateTimestampMs = t1;
+    const account = createAccountDetailWithId();
+    const change: ParsedChangeInfo = {
+      ...createParsedChange(),
+      attention_set: {
+        [`${account._account_id}`]: {
+          account,
+          last_update: t2,
+        },
+      },
+    };
+    sinon.useFakeTimers(t3);
+    sinon
+      .stub(serviceWorker, 'getLatestAttentionSetChanges')
+      .returns(Promise.resolve([change]));
+    const changes = await serviceWorker.getChangesToNotify(account);
+    assert.equal(changes[0], change);
+  });
+});
diff --git a/polygerrit-ui/app/workers/service-worker.ts b/polygerrit-ui/app/workers/service-worker.ts
index e219946..ca1f5dc 100644
--- a/polygerrit-ui/app/workers/service-worker.ts
+++ b/polygerrit-ui/app/workers/service-worker.ts
@@ -4,12 +4,9 @@
  * SPDX-License-Identifier: Apache-2.0
  */
 
-import {readResponsePayload} from '../elements/shared/gr-rest-api-interface/gr-rest-apis/gr-rest-api-helper';
-import {
-  ServiceWorkerMessageType,
-  TRIGGER_NOTIFICATION_UPDATES_MS,
-} from '../services/service-worker-installer';
-import {ParsedChangeInfo} from '../types/types';
+import {AccountDetailInfo} from '../api/rest-api';
+import {ServiceWorkerMessageType} from '../services/service-worker-installer';
+import {ServiceWorker} from './service-worker-class';
 
 /**
  * `self` is for a worker what `window` is for the web app. It is called
@@ -20,49 +17,20 @@
 
 ctx.addEventListener('message', async event => {
   if (event.data?.type !== ServiceWorkerMessageType.TRIGGER_NOTIFICATIONS) {
-    throw new Error(`Unsupported event type: ${event.data?.type}`);
+    // Only this notification message type exists, but we do not throw error.
+    return;
   }
-  const changes = await serviceWorker.getLatestAttentionSetChange();
+  const account = event.data?.account as AccountDetailInfo | undefined;
+  // Message always contains account, but we do not throw error.
+  if (!account?._account_id) return;
+  const latestAttentionChanges = await serviceWorker.getChangesToNotify(
+    account
+  );
   // TODO(milutin): Implement handling more than 1 change
-  if (changes && changes.length > 0) {
-    serviceWorker.showNotification(changes[0]);
+  if (latestAttentionChanges && latestAttentionChanges.length > 0) {
+    serviceWorker.showNotification(latestAttentionChanges[0], account);
   }
 });
 
-class ServiceWorker {
-  latestUpdateTimestampMs?: number;
-
-  showNotification(change: ParsedChangeInfo) {
-    // TODO(milutin): Replace with getReason from attention-set-util.
-    // For get Reason you will need AccountInfo.
-    const body = 'Administrator replied on the change';
-    // TODO(milutin): Implement event.action that
-    // focus on firstWindowClient and open change there.
-    // TODO(milutin): Add gerrit host icon
-    ctx.registration.showNotification(change.subject, {body});
-  }
-
-  async getLatestAttentionSetChange(): Promise<ParsedChangeInfo[]> {
-    // We throttle polling, since there can be many clients triggerring
-    // always only one service worker.
-    if (this.latestUpdateTimestampMs) {
-      const durationFromLatestUpdateMS =
-        Date.now() - this.latestUpdateTimestampMs;
-      if (durationFromLatestUpdateMS < TRIGGER_NOTIFICATION_UPDATES_MS) {
-        return [];
-      }
-    }
-    this.latestUpdateTimestampMs = Date.now();
-    // TODO(milutin): Implement more generic query builder
-    const response = await fetch(
-      '/changes/?O=1000081&S=0&n=25&q=attention%3Aself'
-    );
-    const payload = await readResponsePayload(response);
-    const changes = payload.parsed as unknown as ParsedChangeInfo[] | undefined;
-    // TODO(milutin): Filter changes you are already notified about.
-    return changes ?? [];
-  }
-}
-
 /** Singleton instance being referenced in `onmessage` function above. */
-const serviceWorker = new ServiceWorker();
+const serviceWorker = new ServiceWorker(ctx);